* [PATCH v26 0/4] Add ASPEED AST2600 I2C controller driver
@ 2026-03-09 6:53 Ryan Chen
2026-03-09 6:53 ` [PATCH v26 1/4] dt-bindings: i2c: Split AST2600 binding into a new YAML Ryan Chen
` (3 more replies)
0 siblings, 4 replies; 18+ messages in thread
From: Ryan Chen @ 2026-03-09 6:53 UTC (permalink / raw)
To: jk, andriy.shevchenko, Andi Shyti, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Rayn Chen, Philipp Zabel
Cc: linux-i2c, devicetree, linux-arm-kernel, linux-aspeed,
linux-kernel, openbmc, Ryan Chen
This series adds support for the AST2600 I2C controller “new register
set” implementation.
The AST2600 I2C controller introduces a revised register layout which
separates controller and target functionality into distinct register
blocks, and extends clock divider configuration, packet-based transfer
support, and DMA capabilities compared to the legacy mixed register
layout used on earlier ASPEED SoCs.
The current driver implementation for the AST2600 I2C peripheral is
through the hardware's "compatibility mode", which exposes a register
set that matches the previous generation hardware (AST2500 and earlier).
Instead, add a driver that works in new-register-set mode, to allow the
new features, and will provide support for future hardware that will
not implement compatibility mode.
In order to support the new mode, we need a couple of DT binding changes
to reflect the expanded hardware interfaces: references to a global
register set, and buffer mode selection. Since the binding still
represents the same (AST2600 SoC) physical hardware, we continue to use
the existing compatible string of "aspeed,ast2600-i2c-bus".
However: since we're changing semantics for an existing binding, we
allow backwards compatibility by selecting on presence/absence of the
newly-added properties, and fall back to the old driver (ie., in
compatibility mode) when we detect a DT using the old binding spec.
Specifically:
- ast2600-i2c-bus nodes that provide the `aspeed,global-regs` property
(which is mandatory in the new binding and absent in the legacy
binding) will be successfully probed by the new driver
- ast2600-i2c-bus nodes without `aspeed,global-regs` continue to use the
existing driver (in legacy register mode), ensuring that platforms
with the current DTBs remain functional
Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
---
Changes in v26:
- 1/4: binding reworks based on review feedback
- Link to v25: https://lore.kernel.org/r/20260225-upstream_i2c-v25-0-9f4bdd954f3f@aspeedtech.com
Changes in v25:
- Use b4 to send series.
- Rebase on v7.0-rc1.
- Clarify cover letter and commit logs based on review feedback.
- Remove the i2c-aspeed-core multiplexer infrastructure and
implement driver selection via conditional -ENODEV handling
in individual probe() functions.
- 3/4: incorporate review feedback and refactor new driver
- Link to v24: https://lore.kernel.org/r/20251118014034.820988-1-ryan_chen@aspeedtech.com
Changes in v24:
- aspeed,ast2600-i2c.yaml
- fix make dt_binding_check blank warning.
- Link to v23: https://lore.kernel.org/all/20251117025040.3622984-1-ryan_chen@aspeedtech.com/
Changes in v23:
- update typo patch (1/4) commit message.
- aspeed,ast2600-i2c.yaml
- update reg and description.
- i2c-ast2600.c controller
- replace ast2600_select_i2c_clock to ast2600_i2c_ac_timing_config.
- i2c-ast2600.c target
- I2C_TARGET_MSG_BUF_SIZE 256 to 4096
- remove blank line.
- refine Master comment description to controller
- Link to v22: https://lore.kernel.org/all/20251112085649.1903631-1-ryan_chen@aspeedtech.com/
Changes in v22:
- update patch (1/4) commit message add dts example reason.
- aspeed,ast2600-i2c.yaml @patch (1/4)
- rename ast2600-i2c.yaml to aspeed,ast2600-i2c.yaml.
- update reg, clock-frequency description.
- aspeed,ast2600-i2c.yaml @patch (2/4)
- aspeed,transfer-mode, aspeed,transfer-mode add for ast2600.
- i2c-aspeed-core.c,h @patch (3/4)
- add i2c-aspeed-core allow both old and new device trees using the
same compatible string "aspeed,ast2600-i2c-bus".
- Link to v21: https://lore.kernel.org/all/20251027061240.3427875-1-ryan_chen@aspeedtech.com/
Changes in v21:
- update patch (1/4) commit message
- i2c-ast2600.c
- move rst to local variable in ast2600_i2c_probe().
- Link to v20: https://lore.kernel.org/all/20251021013548.2375190-1-ryan_chen@aspeedtech.com/
Changes in v20:
- ast2600-i2c.yaml
- fix warning at make dt_binding_check.
- Link to v19: https://lore.kernel.org/all/20251020013200.1858325-1-ryan_chen@aspeedtech.com/
Changes in v19:
- Split AST2600 binding into its own YAML file
- Removed `aspeed,ast2600-i2c-bus` from `aspeed,i2c.yaml`
- Added `aspeed,global-regs` and `aspeed,transfer-mode` to AST2600 binding
- Link to v18: https://lore.kernel.org/all/20250820051832.3605405-1-ryan_chen@aspeedtech.com/
Changes in v18:
- refine patch (1/3) commit message (reason for commit not list.)
- i2c-ast2600.c
- remove redundant reset_control_deassert in driver probe.
- remove reset_control_assert(i2c_bus->rst) in driver remove.
- Link to v17: https://lore.kernel.org/all/20250814084156.1650432-1-ryan_chen@aspeedtech.com/
Changes in v17:
- move i2c new mode register and feature into driver commit message.
- aspeed,i2c.yaml
- remove multi-master properties.
- use aspeed,transfer-mode properties for aspeed,enable-byte/enable-dma.
-i2c-ast2600.c
- rename dma_safe_buf to controller_dma_safe_buf.
- fix ast2600_i2c_recover_bus return overflow warnings.
- add ast2600_i2c_target_packet_buff_irq unhandle case.
- add parameter "cmd" in ast2600_i2c_setup_dma_rx,
ast2600_i2c_setup_buff_rx, ast2600_i2c_setup_byte_rx
- use reset_control_deassert replace
devm_reset_control_get_shared_deasserted.
- useaspeed,transfer-mode properties for transfer mode setting.
- change compatible = "aspeed,ast2600-i2cv2" to "aspeed,ast2600-i2c-bus".
- Link to v16: https://lore.kernel.org/all/20250224055936.1804279-1-ryan_chen@aspeedtech.com/
Changes in v16:
- aspeed,i2c.yaml: add aspeed,enable-byte properties for force byte mode.
- i2c-ast2600.c
- change include asm/unaligned.h to linux/unaligned.h.
- add reset timeout councter when slave active timeout.
- modify issue i2c_recovery_bus before slave re-enable.
- add aspeed,enable-byte properties.
- Link to v15: https://lore.kernel.org/all/20241007035235.2254138-1-ryan_chen@aspeedtech.com/
Changes in v15:
- i2c-ast2600.c
- add include unaligned.h
- rename all master -> controller, slave -> target.
- keep multi-master to align property.
- remove no used element in ast2600_i2c_bus.
- Link to v14: https://lore.kernel.org/all/20241002070213.1165263-1-ryan_chen@aspeedtech.com/
Changes in v14:
- aspeed,i2c.yaml
- v13 change people reviewed-by tag, v14 fixed to original people tag,
modify to Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
- struct ast2600_i2c_bus layout optimal.
- ast2600_select_i2c_clock refine.
- ast2600_i2c_recover_bus overridden fix.
- dma_mapping_error() returned error code shadowed modify.
- buffer register in a 4-byte aligned simplified
- remove smbus alert
- Link to v13: https://lore.kernel.org/all/20240819092850.1590758-1-ryan_chen@aspeedtech.com/
Changes in v13:
- separate i2c master and slave driver to be two patchs.
- modify include header list, add bits.h include. remove of*.h
- modify (((x) >> 24) & GENMASK(5, 0)) to (((x) & GENMASK(29, 24)) >> 24)
- modify ast2600_select_i2c_clock function implement.
- modify ast2600_i2c_recover_bus function u32 claim to
u32 state = readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
- Link to v12: https://lore.kernel.org/all/20230714074522.23827-1-ryan_chen@aspeedtech.com/
Changes in v12:
- aspeed,i2c.yaml
- add Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
- i2c-ast2600.c
- update include by alphabetical order
- make just a one TAB and put the last two lines on the single one
- remove no used timing_table structre
- remove enum explicit assinment
- rewritten to avoid this and using loop in ast2600_select_i2c_clock
- use GENMASK for most 0xffff
- remove too many parentheses
- use str_read_write replace read write string
- remove redundant blank line after ast2600_i2c_bus_of_table
- fix wrong multi-line style of the comment
- use macro for i2c standard speeds
- remove useless noise dev_info
- Link to v11: https://lore.kernel.org/all/20230430041712.3247998-1-ryan_chen@aspeedtech.com/
Changes in v11:
- aspeed,i2c.yaml
- no change, the same with v10.
- i2c-ast2600.c
- modify alert_enable from int -> boolean.
- modify dbg string recovery -> recover.
- remove no need to init 0.
- remove new line after break.
- remove unneeded empty line.
- modify dma_alloc_coherent to dmam_alloc_coherent
- modify probe nomem return dev_err_probe
- modify i2c_add_adapter to devm_i2c_adapter
- modify checkpatch: Alignment should match open parenthesis
- modify checkpatch: braces {} should be used on all arms of this statement
- modify checkpatch: Unbalanced braces around else statement
- Link to v10: https://lore.kernel.org/all/20230415012848.1777768-1-ryan_chen@aspeedtech.com/
Changes in v10:
- aspeed,i2c.yaml
- move unevaluatedProperties after allOf.
- remove extra one blank line.
- i2c-ast2600.c
- no change, the same with v8.
- Link to v9: https://lore.kernel.org/all/20230405022825.333246-1-ryan_chen@aspeedtech.com/
Changes in v9:
- aspeed,i2c.yaml
- backoff to v7.
- no fix typo in maintainer's name and email. this would be another patch.
- no remove address-cells, size-cells, this would be another patch.
- use aspeed,enable-dma property instead of aspeed,xfer-mode selection.
- fix allOf and else false properties for aspeed,ast2600-i2cv2.
- i2c-ast2600.c
- no change, the same with v8
- Link to v8: https://lore.kernel.org/all/20230330073259.485606-1-ryan_chen@aspeedtech.com/
Changes in v8:
- aspeed,i2c.yaml
- modify commit message.
- Fix typo in maintainer's name and email.
- remove address-cells, size-cells.
- i2c-ast2600.c
- move "i2c timeout counter" comment description before property_read.
- remove redundant code "return ret" in probe end.
- Link to v7: https://lore.kernel.org/all/20230327092524.3916389-1-ryan_chen@aspeedtech.com/
Changes in v7:
- aspeed,i2c.yaml
- Update ASPEED I2C maintainers email.
- use aspeed,enable-dma property instead of aspeed,xfer-mode selection.
- fix allOf and else false properties for aspeed,ast2600-i2cv2.
- i2c-ast2600.c
- remove aspeed,xfer-mode instead of aspeed,enable-dma mode. buffer mode
is default.
- remove aspeed,timeout instead of i2c-scl-clk-low-timeout-us for
timeout setting.
- Link to v6: https://lore.kernel.org/all/20230226031321.3126756-1-ryan_chen@aspeedtech.com/
Changes in v6:
- remove aspeed,i2cv2.yaml, merge to aspeed,i2c.yaml -add support for
i2cv2 properites.
- i2c-ast2600.c
- fix ast2600_i2c_remove ordering.
- remove ast2600_i2c_probe goto labels, and add dev_err_probe -remove
redundant deb_dbg debug message.
- rename gr_regmap -> global_regs
- Link to v5: https://lore.kernel.org/all/20230220061745.1973981-1-ryan_chen@aspeedtech.com/
Changes in v5:
- remove ast2600-i2c-global.yaml, i2c-ast2600-global.c.
- i2c-ast2600.c
- remove legacy clock divide, all go for new clock divide.
- remove duplicated read isr.
- remove no used driver match
- fix probe return for each labels return.
- global use mfd driver, driver use phandle to regmap read/write.
- rename aspeed,i2c-ast2600.yaml to aspeed,i2cv2.yaml -remove bus-frequency.
- add required aspeed,gr
- add timeout, byte-mode, buff-mode properites.
- Link to v4: https://lore.kernel.org/all/20230201103359.1742140-1-ryan_chen@aspeedtech.com/
Changes in v4:
- fix i2c-ast2600.c driver buffer mode use single buffer conflit in
master slave mode both enable.
- fix kmemleak issue when use dma mode.
- fix typo aspeed,i2c-ast2600.yaml compatible is "aspeed,ast2600-i2c"
- fix typo aspeed,i2c-ast2600.ymal to aspeed,i2c-ast2600.yaml
- Link to v3: https://lore.kernel.org/all/20220516064900.30517-1-ryan_chen@aspeedtech.com/
Changes in v3:
- fix i2c global clock divide default value.
- remove i2c slave no used dev_dbg info.
- Link to v2: https://lore.kernel.org/all/20220413101735.27678-1-ryan_chen@aspeedtech.com/
Changes in v2:
- add i2c global ymal file commit.
- rename file name from new to ast2600.
aspeed-i2c-new-global.c -> i2c-ast2600-global.c
aspeed-i2c-new-global.h -> i2c-ast2600-global.h
i2c-new-aspeed.c -> i2c-ast2600.c
- rename all driver function name to ast2600.
- Link to v1: https://lore.kernel.org/all/20220323004009.943298-1-ryan_chen@aspeedtech.com/
---
Ryan Chen (4):
dt-bindings: i2c: Split AST2600 binding into a new YAML
dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
i2c: ast2600: Add controller driver for AST2600 new register set
i2c: ast2600: Add target mode support
.../bindings/i2c/aspeed,ast2600-i2c.yaml | 91 ++
.../devicetree/bindings/i2c/aspeed,i2c.yaml | 3 +-
drivers/i2c/busses/Makefile | 2 +-
drivers/i2c/busses/i2c-aspeed.c | 5 +
drivers/i2c/busses/i2c-ast2600.c | 1551 ++++++++++++++++++++
5 files changed, 1649 insertions(+), 3 deletions(-)
---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20260223-upstream_i2c-ebd07f89739c
Best regards,
--
Ryan Chen <ryan_chen@aspeedtech.com>
^ permalink raw reply [flat|nested] 18+ messages in thread
* [PATCH v26 1/4] dt-bindings: i2c: Split AST2600 binding into a new YAML
2026-03-09 6:53 [PATCH v26 0/4] Add ASPEED AST2600 I2C controller driver Ryan Chen
@ 2026-03-09 6:53 ` Ryan Chen
2026-03-09 6:53 ` [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties Ryan Chen
` (2 subsequent siblings)
3 siblings, 0 replies; 18+ messages in thread
From: Ryan Chen @ 2026-03-09 6:53 UTC (permalink / raw)
To: jk, andriy.shevchenko, Andi Shyti, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Rayn Chen, Philipp Zabel
Cc: linux-i2c, devicetree, linux-arm-kernel, linux-aspeed,
linux-kernel, openbmc, Ryan Chen
The AST2600 I2C controller introduces a completely new register layout
with separate controller and target register blocks, unlike the mixed
register layout used by AST2400/AST2500.
Move AST2600 I2C binding from aspeed,i2c.yaml to a dedicated
aspeed,ast2600-i2c.yaml schema.
Besides the split, this also adjusts for AST2600-specific requirements.
- require two reg regions (controller register block + buffer block)
- use clock-frequency for bus speed description
- interrupts are required on AST2600
- use correct DTS coding style in example
No compatible strings are changed.
Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
---
Changes in v26:
- commit message: include details of changes from original binding
- fix example property ordering to follow DTS coding style
- use consistent "AST2600" naming
---
.../bindings/i2c/aspeed,ast2600-i2c.yaml | 62 ++++++++++++++++++++++
.../devicetree/bindings/i2c/aspeed,i2c.yaml | 3 +-
2 files changed, 63 insertions(+), 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
new file mode 100644
index 000000000000..de2c359037da
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/aspeed,ast2600-i2c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ASPEED I2C on the AST2600 SoCs
+
+maintainers:
+ - Ryan Chen <ryan_chen@aspeedtech.com>
+
+allOf:
+ - $ref: /schemas/i2c/i2c-controller.yaml#
+
+properties:
+ compatible:
+ enum:
+ - aspeed,ast2600-i2c-bus
+
+ reg:
+ items:
+ - description: controller registers
+ - description: controller buffer space
+
+ interrupts:
+ maxItems: 1
+
+ clocks:
+ maxItems: 1
+
+ clock-frequency:
+ description: Desired operating frequency of the I2C bus in Hz.
+ minimum: 500
+ maximum: 4000000
+ default: 100000
+
+ resets:
+ maxItems: 1
+
+required:
+ - reg
+ - compatible
+ - clocks
+ - resets
+ - interrupts
+
+unevaluatedProperties: false
+
+examples:
+ - |
+ #include <dt-bindings/clock/aspeed-clock.h>
+ #include <dt-bindings/interrupt-controller/arm-gic.h>
+ i2c@80 {
+ compatible = "aspeed,ast2600-i2c-bus";
+ reg = <0x80 0x80>, <0xc00 0x20>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ clocks = <&syscon ASPEED_CLK_APB>;
+ resets = <&syscon ASPEED_RESET_I2C>;
+ clock-frequency = <100000>;
+ interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
+ };
diff --git a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
index 5b9bd2feda3b..d4e4f412feba 100644
--- a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
@@ -4,7 +4,7 @@
$id: http://devicetree.org/schemas/i2c/aspeed,i2c.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
-title: ASPEED I2C on the AST24XX, AST25XX, and AST26XX SoCs
+title: ASPEED I2C on the AST24XX, AST25XX SoCs
maintainers:
- Rayn Chen <rayn_chen@aspeedtech.com>
@@ -17,7 +17,6 @@ properties:
enum:
- aspeed,ast2400-i2c-bus
- aspeed,ast2500-i2c-bus
- - aspeed,ast2600-i2c-bus
reg:
minItems: 1
--
2.34.1
^ permalink raw reply related [flat|nested] 18+ messages in thread
* [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-09 6:53 [PATCH v26 0/4] Add ASPEED AST2600 I2C controller driver Ryan Chen
2026-03-09 6:53 ` [PATCH v26 1/4] dt-bindings: i2c: Split AST2600 binding into a new YAML Ryan Chen
@ 2026-03-09 6:53 ` Ryan Chen
2026-03-13 23:21 ` Rob Herring
2026-03-09 6:53 ` [PATCH v26 3/4] i2c: ast2600: Add controller driver for AST2600 new register set Ryan Chen
2026-03-09 6:53 ` [PATCH v26 4/4] i2c: ast2600: Add target mode support Ryan Chen
3 siblings, 1 reply; 18+ messages in thread
From: Ryan Chen @ 2026-03-09 6:53 UTC (permalink / raw)
To: jk, andriy.shevchenko, Andi Shyti, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Rayn Chen, Philipp Zabel
Cc: linux-i2c, devicetree, linux-arm-kernel, linux-aspeed,
linux-kernel, openbmc, Ryan Chen
The AST2600 I2C controller supports three transfer modes (byte, buffer,
DMA). Add "aspeed,transfer-mode" so DT can select the preferred transfer
method per controller instance. Also add the "aspeed,global-regs"
phandle to reference the AST2600 global registers syscon/regmap used by
the controller.
These properties apply only to the AST2600 binding and are not part of
the legacy binding, which uses a mixed controller/target register layout
and does not have the split register blocks or these new configuration
registers. Legacy DTs remain unchanged.
Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
---
.../bindings/i2c/aspeed,ast2600-i2c.yaml | 29 ++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
index de2c359037da..323e4f9b290a 100644
--- a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
@@ -37,6 +37,33 @@ properties:
resets:
maxItems: 1
+ aspeed,transfer-mode:
+ description: |
+ ASPEED ast2600 platform equipped with 16 I2C controllers each i2c controller
+ have 1 byte transfer buffer(byte mode), 32 bytes buffer(buffer mode), and
+ share a DMA engine.
+ Select I2C transfer mode for this controller. Supported values are:
+ - "byte": Use 1 byte for i2c transmit (1-byte buffer).
+ - "buffer": Use buffer (32-byte buffer) for i2c transmit. (default)
+ Better performance then byte mode.
+ - "dma": Each controller DMA mode is shared DMA engine. The AST2600 SoC
+ provides a single DMA engine shared for 16 I2C controllers,
+ so only a limited number of controllers can use DMA simultaneously.
+ Therefore, the DTS must explicitly assign which controllers are
+ configured to use DMA.
+ On AST2600, each controller supports all three modes.
+ If not specified, buffer mode is used by default.
+ enum:
+ - byte
+ - buffer
+ - dma
+
+ aspeed,global-regs:
+ $ref: /schemas/types.yaml#/definitions/phandle
+ description:
+ Phandle reference to the i2c global syscon node, containing the
+ SoC-common i2c register set.
+
required:
- reg
- compatible
@@ -59,4 +86,6 @@ examples:
resets = <&syscon ASPEED_RESET_I2C>;
clock-frequency = <100000>;
interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
+ aspeed,global-regs = <&i2c_global>;
+ aspeed,transfer-mode = "buffer";
};
--
2.34.1
^ permalink raw reply related [flat|nested] 18+ messages in thread
* [PATCH v26 3/4] i2c: ast2600: Add controller driver for AST2600 new register set
2026-03-09 6:53 [PATCH v26 0/4] Add ASPEED AST2600 I2C controller driver Ryan Chen
2026-03-09 6:53 ` [PATCH v26 1/4] dt-bindings: i2c: Split AST2600 binding into a new YAML Ryan Chen
2026-03-09 6:53 ` [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties Ryan Chen
@ 2026-03-09 6:53 ` Ryan Chen
2026-03-09 6:53 ` [PATCH v26 4/4] i2c: ast2600: Add target mode support Ryan Chen
3 siblings, 0 replies; 18+ messages in thread
From: Ryan Chen @ 2026-03-09 6:53 UTC (permalink / raw)
To: jk, andriy.shevchenko, Andi Shyti, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Rayn Chen, Philipp Zabel
Cc: linux-i2c, devicetree, linux-arm-kernel, linux-aspeed,
linux-kernel, openbmc, Ryan Chen
The AST2600 introduces a new I2C controller register layout, selectable
at runtime via global control registers. Compared to the legacy layout
used on AST2400/AST2500, the new layout separates controller (master)
and target (slave) registers and adds support for packet-based transfers
The new register set extends the hardware capabilities with:
- Enhanced clock divider configuration for improved timing precision
- tCKHighMin timing control for SCL high pulse width
- Dual pool buffer mode (separate Tx/Rx buffers)
- Extended DMA support with larger buffer size and alignment handling
- Dedicated DMA buffers for controller and target directions
- Hardware-assisted bus recovery and timeout mechanisms
This patch adds an AST2600-specific I2C controller driver implementing
the new register layout, including support for packet-based transfers
and byte, buffer and DMA transfer modes.
The legacy and new register layouts represent the same AST2600 I2C
controller IP and therefore share the existing compatible string:
"aspeed,ast2600-i2c-bus"
To preserve DT ABI compatibility, driver selection is performed at probe
time based on DT contents. In particular, the new binding requires the
`aspeed,global-regs` phandle, which is absent from legacy DTBs:
- The new driver only probes successfully when `aspeed,global-regs` is
present.
- The existing i2c-aspeed driver returns -ENODEV for AST2600 nodes that
provide `aspeed,global-regs`, allowing the new driver to bind.
Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
---
Changes in v25:
- Rename AST2600_I2CM_SMBUS_ALT to AST2600_I2CM_SMBUS_ALERT.
- Refactor transfer mode handling using setup_tx/setup_rx helpers.
- Rework DMA handling to use pre-allocated buffers and reduce
mapping overhead in interrupt context.
- Fix IRQ status checks to use consistent (sts & value) style.
- Move device_property_read_bool() to probe().
- Improve probe error handling.
- Handle timeout condition in target_byte_irq().
- Rename "package" to "packet".
- Remove target reset when master wait_for_completion_timeout().
---
drivers/i2c/busses/Makefile | 2 +-
drivers/i2c/busses/i2c-aspeed.c | 5 +
drivers/i2c/busses/i2c-ast2600.c | 988 +++++++++++++++++++++++++++++++++++++++
3 files changed, 994 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 547123ab351f..ece201a67d41 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -37,7 +37,7 @@ obj-$(CONFIG_I2C_POWERMAC) += i2c-powermac.o
obj-$(CONFIG_I2C_ALTERA) += i2c-altera.o
obj-$(CONFIG_I2C_AMD_MP2) += i2c-amd-mp2-pci.o i2c-amd-mp2-plat.o
obj-$(CONFIG_I2C_AMD_ASF) += i2c-amd-asf-plat.o
-obj-$(CONFIG_I2C_ASPEED) += i2c-aspeed.o
+obj-$(CONFIG_I2C_ASPEED) += i2c-aspeed.o i2c-ast2600.o
obj-$(CONFIG_I2C_AT91) += i2c-at91.o
i2c-at91-y := i2c-at91-core.o i2c-at91-master.o
i2c-at91-$(CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL) += i2c-at91-slave.o
diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index a26b74c71206..8286fd2cd130 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -22,6 +22,7 @@
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
+#include <linux/property.h>
#include <linux/reset.h>
#include <linux/slab.h>
@@ -1002,6 +1003,10 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
struct clk *parent_clk;
int irq, ret;
+ if (device_is_compatible(&pdev->dev, "aspeed,ast2600-i2c-bus") &&
+ device_property_present(&pdev->dev, "aspeed,global-regs"))
+ return -ENODEV;
+
bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
if (!bus)
return -ENOMEM;
diff --git a/drivers/i2c/busses/i2c-ast2600.c b/drivers/i2c/busses/i2c-ast2600.c
new file mode 100644
index 000000000000..c3e4abb426e2
--- /dev/null
+++ b/drivers/i2c/busses/i2c-ast2600.c
@@ -0,0 +1,988 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ASPEED AST2600 new register set I2C controller driver
+ *
+ * Copyright (C) 2026 ASPEED Technology Inc.
+ */
+#include <linux/array_size.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/i2c-smbus.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/minmax.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+#include <linux/string_helpers.h>
+#include <linux/unaligned.h>
+
+#define AST2600_I2CG_ISR 0x00
+#define AST2600_I2CG_SLAVE_ISR 0x04
+#define AST2600_I2CG_OWNER 0x08
+#define AST2600_I2CG_CTRL 0x0C
+#define AST2600_I2CG_CLK_DIV_CTRL 0x10
+
+#define AST2600_I2CG_SLAVE_PKT_NAK BIT(4)
+#define AST2600_I2CG_M_S_SEPARATE_INTR BIT(3)
+#define AST2600_I2CG_CTRL_NEW_REG BIT(2)
+#define AST2600_I2CG_CTRL_NEW_CLK_DIV BIT(1)
+#define AST2600_GLOBAL_INIT \
+ (AST2600_I2CG_CTRL_NEW_REG | AST2600_I2CG_CTRL_NEW_CLK_DIV)
+/*
+ * APB clk : 100Mhz
+ * div : scl : baseclk [APB/((div/2) + 1)] : tBuf [1/bclk * 16]
+ * I2CG10[31:24] base clk4 for i2c auto recovery timeout counter (0xC6)
+ * I2CG10[23:16] base clk3 for Standard-mode (100Khz) min tBuf 4.7us
+ * 0x3c : 100.8Khz : 3.225Mhz : 4.96us
+ * 0x3d : 99.2Khz : 3.174Mhz : 5.04us
+ * 0x3e : 97.65Khz : 3.125Mhz : 5.12us
+ * 0x40 : 97.75Khz : 3.03Mhz : 5.28us
+ * 0x41 : 99.5Khz : 2.98Mhz : 5.36us (default)
+ * I2CG10[15:8] base clk2 for Fast-mode (400Khz) min tBuf 1.3us
+ * 0x12 : 400Khz : 10Mhz : 1.6us
+ * I2CG10[7:0] base clk1 for Fast-mode Plus (1Mhz) min tBuf 0.5us
+ * 0x08 : 1Mhz : 20Mhz : 0.8us
+ */
+#define I2CCG_DIV_CTRL 0xC6411208
+
+/* 0x00 : I2CC Controller/Target Function Control Register */
+#define AST2600_I2CC_FUN_CTRL 0x00
+#define AST2600_I2CC_SLAVE_ADDR_RX_EN BIT(20)
+#define AST2600_I2CC_MASTER_RETRY_MASK GENMASK(19, 18)
+#define AST2600_I2CC_MASTER_RETRY(x) (((x) & GENMASK(1, 0)) << 18)
+#define AST2600_I2CC_BUS_AUTO_RELEASE BIT(17)
+#define AST2600_I2CC_M_SDA_LOCK_EN BIT(16)
+#define AST2600_I2CC_MULTI_MASTER_DIS BIT(15)
+#define AST2600_I2CC_M_SCL_DRIVE_EN BIT(14)
+#define AST2600_I2CC_MSB_STS BIT(9)
+#define AST2600_I2CC_SDA_DRIVE_1T_EN BIT(8)
+#define AST2600_I2CC_M_SDA_DRIVE_1T_EN BIT(7)
+#define AST2600_I2CC_M_HIGH_SPEED_EN BIT(6)
+/* reserver 5 : 2 */
+#define AST2600_I2CC_SLAVE_EN BIT(1)
+#define AST2600_I2CC_MASTER_EN BIT(0)
+
+/* 0x04 : I2CC Controller/Target Clock and AC Timing Control Register #1 */
+#define AST2600_I2CC_AC_TIMING 0x04
+#define AST2600_I2CC_TTIMEOUT(x) (((x) & GENMASK(4, 0)) << 24)
+#define AST2600_I2CC_TCKHIGHMIN(x) (((x) & GENMASK(3, 0)) << 20)
+#define AST2600_I2CC_TCKHIGH(x) (((x) & GENMASK(3, 0)) << 16)
+#define AST2600_I2CC_TCKLOW(x) (((x) & GENMASK(3, 0)) << 12)
+#define AST2600_I2CC_THDDAT(x) (((x) & GENMASK(1, 0)) << 10)
+#define AST2600_I2CC_TOUTBASECLK(x) (((x) & GENMASK(1, 0)) << 8)
+#define AST2600_I2CC_TBASECLK(x) ((x) & GENMASK(3, 0))
+#define AST2600_I2CC_AC_TIMING_MASK GENMASK(23, 0)
+
+/* 0x08 : I2CC Controller/Target Transmit/Receive Byte Buffer Register */
+#define AST2600_I2CC_STS_AND_BUFF 0x08
+#define AST2600_I2CC_TX_DIR_MASK GENMASK(31, 29)
+#define AST2600_I2CC_SDA_OE BIT(28)
+#define AST2600_I2CC_SDA_O BIT(27)
+#define AST2600_I2CC_SCL_OE BIT(26)
+#define AST2600_I2CC_SCL_O BIT(25)
+
+#define AST2600_I2CC_SCL_LINE_STS BIT(18)
+#define AST2600_I2CC_SDA_LINE_STS BIT(17)
+#define AST2600_I2CC_BUS_BUSY_STS BIT(16)
+
+#define AST2600_I2CC_GET_RX_BUFF(x) (((x) >> 8) & GENMASK(7, 0))
+
+/* 0x0C : I2CC Controller/Target Pool Buffer Control Register */
+#define AST2600_I2CC_BUFF_CTRL 0x0C
+#define AST2600_I2CC_GET_RX_BUF_LEN(x) (((x) & GENMASK(29, 24)) >> 24)
+#define AST2600_I2CC_SET_RX_BUF_LEN(x) (((((x) - 1) & GENMASK(4, 0)) << 16) | BIT(0))
+#define AST2600_I2CC_SET_TX_BUF_LEN(x) (((((x) - 1) & GENMASK(4, 0)) << 8) | BIT(0))
+#define AST2600_I2CC_GET_TX_BUF_LEN(x) ((((x) & GENMASK(12, 8)) >> 8) + 1)
+
+/* 0x10 : I2CM Controller Interrupt Control Register */
+#define AST2600_I2CM_IER 0x10
+/* 0x14 : I2CM Controller Interrupt Status Register : WC */
+#define AST2600_I2CM_ISR 0x14
+
+#define AST2600_I2CM_PKT_TIMEOUT BIT(18)
+#define AST2600_I2CM_PKT_ERROR BIT(17)
+#define AST2600_I2CM_PKT_DONE BIT(16)
+
+#define AST2600_I2CM_BUS_RECOVER_FAIL BIT(15)
+#define AST2600_I2CM_SDA_DL_TO BIT(14)
+#define AST2600_I2CM_BUS_RECOVER BIT(13)
+#define AST2600_I2CM_SMBUS_ALERT BIT(12)
+
+#define AST2600_I2CM_SCL_LOW_TO BIT(6)
+#define AST2600_I2CM_ABNORMAL BIT(5)
+#define AST2600_I2CM_NORMAL_STOP BIT(4)
+#define AST2600_I2CM_ARBIT_LOSS BIT(3)
+#define AST2600_I2CM_RX_DONE BIT(2)
+#define AST2600_I2CM_TX_NAK BIT(1)
+#define AST2600_I2CM_TX_ACK BIT(0)
+
+/* 0x18 : I2CM Controller Command/Status Register */
+#define AST2600_I2CM_CMD_STS 0x18
+#define AST2600_I2CM_PKT_ADDR(x) (((x) & GENMASK(6, 0)) << 24)
+#define AST2600_I2CM_PKT_EN BIT(16)
+#define AST2600_I2CM_SDA_OE_OUT_DIR BIT(15)
+#define AST2600_I2CM_SDA_O_OUT_DIR BIT(14)
+#define AST2600_I2CM_SCL_OE_OUT_DIR BIT(13)
+#define AST2600_I2CM_SCL_O_OUT_DIR BIT(12)
+#define AST2600_I2CM_RECOVER_CMD_EN BIT(11)
+
+#define AST2600_I2CM_RX_DMA_EN BIT(9)
+#define AST2600_I2CM_TX_DMA_EN BIT(8)
+/* Command Bit */
+#define AST2600_I2CM_RX_BUFF_EN BIT(7)
+#define AST2600_I2CM_TX_BUFF_EN BIT(6)
+#define AST2600_I2CM_STOP_CMD BIT(5)
+#define AST2600_I2CM_RX_CMD_LAST BIT(4)
+#define AST2600_I2CM_RX_CMD BIT(3)
+
+#define AST2600_I2CM_TX_CMD BIT(1)
+#define AST2600_I2CM_START_CMD BIT(0)
+
+/* 0x1C : I2CM Controller DMA Transfer Length Register */
+#define AST2600_I2CM_DMA_LEN 0x1C
+/* Tx Rx support length 1 ~ 4096 */
+#define AST2600_I2CM_SET_RX_DMA_LEN(x) ((((x) & GENMASK(11, 0)) << 16) | BIT(31))
+#define AST2600_I2CM_SET_TX_DMA_LEN(x) (((x) & GENMASK(11, 0)) | BIT(15))
+
+/* 0x20 : I2CS Target Interrupt Control Register */
+#define AST2600_I2CS_IER 0x20
+/* 0x24 : I2CS Target Interrupt Status Register */
+#define AST2600_I2CS_ISR 0x24
+
+#define AST2600_I2CS_ADDR_INDICATE_MASK GENMASK(31, 30)
+#define AST2600_I2CS_SLAVE_PENDING BIT(29)
+
+#define AST2600_I2CS_WAIT_TX_DMA BIT(25)
+#define AST2600_I2CS_WAIT_RX_DMA BIT(24)
+
+#define AST2600_I2CS_ADDR3_NAK BIT(22)
+#define AST2600_I2CS_ADDR2_NAK BIT(21)
+#define AST2600_I2CS_ADDR1_NAK BIT(20)
+
+#define AST2600_I2CS_ADDR_MASK GENMASK(19, 18)
+#define AST2600_I2CS_PKT_ERROR BIT(17)
+#define AST2600_I2CS_PKT_DONE BIT(16)
+#define AST2600_I2CS_INACTIVE_TO BIT(15)
+
+#define AST2600_I2CS_SLAVE_MATCH BIT(7)
+#define AST2600_I2CS_ABNOR_STOP BIT(5)
+#define AST2600_I2CS_STOP BIT(4)
+#define AST2600_I2CS_RX_DONE_NAK BIT(3)
+#define AST2600_I2CS_RX_DONE BIT(2)
+#define AST2600_I2CS_TX_NAK BIT(1)
+#define AST2600_I2CS_TX_ACK BIT(0)
+
+/* 0x28 : I2CS Target CMD/Status Register */
+#define AST2600_I2CS_CMD_STS 0x28
+#define AST2600_I2CS_ACTIVE_ALL GENMASK(18, 17)
+#define AST2600_I2CS_PKT_MODE_EN BIT(16)
+#define AST2600_I2CS_AUTO_NAK_NOADDR BIT(15)
+#define AST2600_I2CS_AUTO_NAK_EN BIT(14)
+
+#define AST2600_I2CS_ALT_EN BIT(10)
+#define AST2600_I2CS_RX_DMA_EN BIT(9)
+#define AST2600_I2CS_TX_DMA_EN BIT(8)
+#define AST2600_I2CS_RX_BUFF_EN BIT(7)
+#define AST2600_I2CS_TX_BUFF_EN BIT(6)
+#define AST2600_I2CS_RX_CMD_LAST BIT(4)
+
+#define AST2600_I2CS_TX_CMD BIT(2)
+
+#define AST2600_I2CS_DMA_LEN 0x2C
+#define AST2600_I2CS_SET_RX_DMA_LEN(x) (((((x) - 1) & GENMASK(11, 0)) << 16) | BIT(31))
+#define AST2600_I2CS_SET_TX_DMA_LEN(x) ((((x) - 1) & GENMASK(11, 0)) | BIT(15))
+
+/* I2CM Controller DMA Tx Buffer Register */
+#define AST2600_I2CM_TX_DMA 0x30
+/* I2CM Controller DMA Rx Buffer Register */
+#define AST2600_I2CM_RX_DMA 0x34
+/* I2CS Target DMA Tx Buffer Register */
+#define AST2600_I2CS_TX_DMA 0x38
+/* I2CS Target DMA Rx Buffer Register */
+#define AST2600_I2CS_RX_DMA 0x3C
+
+#define AST2600_I2CS_ADDR_CTRL 0x40
+
+#define AST2600_I2CS_ADDR3_MASK GENMASK(22, 16)
+#define AST2600_I2CS_ADDR2_MASK GENMASK(14, 8)
+#define AST2600_I2CS_ADDR1_MASK GENMASK(6, 0)
+
+#define AST2600_I2CM_DMA_LEN_STS 0x48
+#define AST2600_I2CS_DMA_LEN_STS 0x4C
+
+#define AST2600_I2C_GET_TX_DMA_LEN(x) ((x) & GENMASK(12, 0))
+#define AST2600_I2C_GET_RX_DMA_LEN(x) (((x) & GENMASK(28, 16)) >> 16)
+
+/* 0x40 : Target Device Address Register */
+#define AST2600_I2CS_ADDR3_ENABLE BIT(23)
+#define AST2600_I2CS_ADDR3(x) ((x) << 16)
+#define AST2600_I2CS_ADDR2_ENABLE BIT(15)
+#define AST2600_I2CS_ADDR2(x) ((x) << 8)
+#define AST2600_I2CS_ADDR1_ENABLE BIT(7)
+#define AST2600_I2CS_ADDR1(x) (x)
+
+#define I2C_TARGET_MSG_BUF_SIZE 4096
+
+#define AST2600_I2C_DMA_SIZE 4096
+
+#define CONTROLLER_TRIGGER_LAST_STOP (AST2600_I2CM_RX_CMD_LAST | AST2600_I2CM_STOP_CMD)
+#define TARGET_TRIGGER_CMD (AST2600_I2CS_ACTIVE_ALL | AST2600_I2CS_PKT_MODE_EN)
+
+#define AST_I2C_TIMEOUT_CLK 0x1
+
+enum xfer_mode {
+ BYTE_MODE,
+ BUFF_MODE,
+ DMA_MODE,
+};
+
+struct ast2600_i2c_bus {
+ struct i2c_adapter adap;
+ struct device *dev;
+ void __iomem *reg_base;
+ struct regmap *global_regs;
+ struct clk *clk;
+ struct i2c_timings timing_info;
+ struct completion cmd_complete;
+ struct i2c_msg *msgs;
+ u8 *controller_dma_buf;
+ dma_addr_t controller_dma_addr;
+ u32 apb_clk;
+ u32 timeout;
+ int irq;
+ int cmd_err;
+ int msgs_index;
+ int msgs_count;
+ int controller_xfer_cnt;
+ size_t buf_index;
+ size_t buf_size;
+ enum xfer_mode mode;
+ bool multi_master;
+ /* Buffer mode */
+ void __iomem *buf_base;
+ int (*setup_tx)(u32 cmd, struct ast2600_i2c_bus *i2c_bus);
+ int (*setup_rx)(u32 cmd, struct ast2600_i2c_bus *i2c_bus);
+};
+
+static void ast2600_i2c_ac_timing_config(struct ast2600_i2c_bus *i2c_bus)
+{
+ unsigned long base_clk[16];
+ int baseclk_idx = 0;
+ int divisor = 0;
+ u32 clk_div_reg;
+ u32 scl_low;
+ u32 scl_high;
+ u32 data;
+
+ regmap_read(i2c_bus->global_regs, AST2600_I2CG_CLK_DIV_CTRL, &clk_div_reg);
+
+ for (int i = 0; i < ARRAY_SIZE(base_clk); i++) {
+ if (i == 0)
+ base_clk[i] = i2c_bus->apb_clk;
+ else if (i < 5)
+ base_clk[i] = (i2c_bus->apb_clk * 2) /
+ (((clk_div_reg >> ((i - 1) * 8)) & GENMASK(7, 0)) + 2);
+ else
+ base_clk[i] = base_clk[4] >> (i - 4);
+
+ if ((base_clk[i] / i2c_bus->timing_info.bus_freq_hz) <= 32) {
+ baseclk_idx = i;
+ divisor = DIV_ROUND_UP(base_clk[i], i2c_bus->timing_info.bus_freq_hz);
+ break;
+ }
+ }
+ baseclk_idx = min(baseclk_idx, 15);
+ divisor = min(divisor, 32);
+ scl_low = min(divisor * 9 / 16 - 1, 15);
+ scl_high = (divisor - scl_low - 2) & GENMASK(3, 0);
+ data = (scl_high - 1) << 20 | scl_high << 16 | scl_low << 12 | baseclk_idx;
+ if (i2c_bus->timeout) {
+ data |= AST2600_I2CC_TOUTBASECLK(AST_I2C_TIMEOUT_CLK);
+ data |= AST2600_I2CC_TTIMEOUT(i2c_bus->timeout);
+ }
+
+ writel(data, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+}
+
+static int ast2600_i2c_recover_bus(struct ast2600_i2c_bus *i2c_bus)
+{
+ u32 state = readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ int ret = 0;
+ u32 ctrl;
+ int r;
+
+ dev_dbg(i2c_bus->dev, "%d-bus recovery bus [%x]\n", i2c_bus->adap.nr, state);
+
+ /* reset controller */
+ ctrl = readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ writel(ctrl & ~AST2600_I2CC_MASTER_EN, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ writel(ctrl, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+
+ reinit_completion(&i2c_bus->cmd_complete);
+ i2c_bus->cmd_err = 0;
+
+ /* Check SDA/SCL status in the status register. */
+ state = readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ if (!(state & AST2600_I2CC_SDA_LINE_STS) && (state & AST2600_I2CC_SCL_LINE_STS)) {
+ writel(AST2600_I2CM_RECOVER_CMD_EN, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
+ r = wait_for_completion_timeout(&i2c_bus->cmd_complete, i2c_bus->adap.timeout);
+ if (r == 0) {
+ dev_dbg(i2c_bus->dev, "recovery timed out\n");
+ return -ETIMEDOUT;
+ } else if (i2c_bus->cmd_err) {
+ dev_dbg(i2c_bus->dev, "recovery error\n");
+ ret = -EPROTO;
+ }
+ }
+
+ /* Recovery done */
+ state = readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ if (state & AST2600_I2CC_BUS_BUSY_STS) {
+ dev_dbg(i2c_bus->dev, "Can't recover bus [%x]\n", state);
+ ret = -EPROTO;
+ }
+
+ return ret;
+}
+
+static int ast2600_i2c_setup_dma_tx(u32 cmd, struct ast2600_i2c_bus *i2c_bus)
+{
+ struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
+ int xfer_len = msg->len - i2c_bus->controller_xfer_cnt;
+
+ cmd |= AST2600_I2CM_PKT_EN;
+
+ if (xfer_len > AST2600_I2C_DMA_SIZE)
+ xfer_len = AST2600_I2C_DMA_SIZE;
+ else if (i2c_bus->msgs_index + 1 == i2c_bus->msgs_count)
+ cmd |= AST2600_I2CM_STOP_CMD;
+
+ if (cmd & AST2600_I2CM_START_CMD)
+ cmd |= AST2600_I2CM_PKT_ADDR(msg->addr);
+
+ if (xfer_len) {
+ memcpy(i2c_bus->controller_dma_buf, msg->buf, xfer_len);
+ cmd |= AST2600_I2CM_TX_DMA_EN | AST2600_I2CM_TX_CMD;
+ writel(AST2600_I2CM_SET_TX_DMA_LEN(xfer_len - 1),
+ i2c_bus->reg_base + AST2600_I2CM_DMA_LEN);
+ }
+
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
+
+ return 0;
+}
+
+static int ast2600_i2c_setup_buff_tx(u32 cmd, struct ast2600_i2c_bus *i2c_bus)
+{
+ struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
+ int xfer_len = msg->len - i2c_bus->controller_xfer_cnt;
+ u32 wbuf_dword;
+ int i;
+
+ cmd |= AST2600_I2CM_PKT_EN;
+
+ if (xfer_len > i2c_bus->buf_size)
+ xfer_len = i2c_bus->buf_size;
+ else if (i2c_bus->msgs_index + 1 == i2c_bus->msgs_count)
+ cmd |= AST2600_I2CM_STOP_CMD;
+
+ if (cmd & AST2600_I2CM_START_CMD)
+ cmd |= AST2600_I2CM_PKT_ADDR(msg->addr);
+
+ if (xfer_len) {
+ cmd |= AST2600_I2CM_TX_BUFF_EN | AST2600_I2CM_TX_CMD;
+ /*
+ * The controller's buffer register supports dword writes only.
+ * Therefore, write dwords to the buffer register in a 4-byte aligned,
+ * and write the remaining unaligned data at the end.
+ */
+ for (i = 0; i < xfer_len; i += 4) {
+ int xfer_cnt = i2c_bus->controller_xfer_cnt + i;
+
+ switch (min(xfer_len - i, 4) % 4) {
+ case 1:
+ wbuf_dword = msg->buf[xfer_cnt];
+ break;
+ case 2:
+ wbuf_dword = get_unaligned_le16(&msg->buf[xfer_cnt]);
+ break;
+ case 3:
+ wbuf_dword = get_unaligned_le24(&msg->buf[xfer_cnt]);
+ break;
+ default:
+ wbuf_dword = get_unaligned_le32(&msg->buf[xfer_cnt]);
+ break;
+ }
+ writel(wbuf_dword, i2c_bus->buf_base + i);
+ }
+ writel(AST2600_I2CC_SET_TX_BUF_LEN(xfer_len),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ }
+
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
+
+ return 0;
+}
+
+static int ast2600_i2c_setup_byte_tx(u32 cmd, struct ast2600_i2c_bus *i2c_bus)
+{
+ struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
+ int xfer_len;
+
+ xfer_len = msg->len - i2c_bus->controller_xfer_cnt;
+
+ cmd |= AST2600_I2CM_PKT_EN;
+
+ if (cmd & AST2600_I2CM_START_CMD)
+ cmd |= AST2600_I2CM_PKT_ADDR(msg->addr);
+
+ if ((i2c_bus->msgs_index + 1 == i2c_bus->msgs_count) &&
+ ((i2c_bus->controller_xfer_cnt + 1) == msg->len))
+ cmd |= AST2600_I2CM_STOP_CMD;
+
+ if (xfer_len) {
+ cmd |= AST2600_I2CM_TX_CMD;
+ writel(msg->buf[i2c_bus->controller_xfer_cnt],
+ i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ }
+
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
+
+ return 0;
+}
+
+static int ast2600_i2c_setup_dma_rx(u32 cmd, struct ast2600_i2c_bus *i2c_bus)
+{
+ struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
+ int xfer_len = msg->len - i2c_bus->controller_xfer_cnt;
+
+ cmd |= AST2600_I2CM_PKT_EN | AST2600_I2CM_RX_DMA_EN | AST2600_I2CM_RX_CMD;
+
+ if (msg->flags & I2C_M_RECV_LEN)
+ xfer_len = 1;
+ else if (xfer_len > AST2600_I2C_DMA_SIZE)
+ xfer_len = AST2600_I2C_DMA_SIZE;
+ else if (i2c_bus->msgs_index + 1 == i2c_bus->msgs_count)
+ cmd |= CONTROLLER_TRIGGER_LAST_STOP;
+
+ writel(AST2600_I2CM_SET_RX_DMA_LEN(xfer_len - 1), i2c_bus->reg_base + AST2600_I2CM_DMA_LEN);
+
+ if (cmd & AST2600_I2CM_START_CMD)
+ cmd |= AST2600_I2CM_PKT_ADDR(msg->addr);
+
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
+
+ return 0;
+}
+
+static int ast2600_i2c_setup_buff_rx(u32 cmd, struct ast2600_i2c_bus *i2c_bus)
+{
+ struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
+ int xfer_len = msg->len - i2c_bus->controller_xfer_cnt;
+
+ cmd |= AST2600_I2CM_PKT_EN | AST2600_I2CM_RX_BUFF_EN | AST2600_I2CM_RX_CMD;
+
+ if (cmd & AST2600_I2CM_START_CMD)
+ cmd |= AST2600_I2CM_PKT_ADDR(msg->addr);
+
+ if (msg->flags & I2C_M_RECV_LEN) {
+ dev_dbg(i2c_bus->dev, "smbus read\n");
+ xfer_len = 1;
+ } else if (xfer_len > i2c_bus->buf_size) {
+ xfer_len = i2c_bus->buf_size;
+ } else if (i2c_bus->msgs_index + 1 == i2c_bus->msgs_count) {
+ cmd |= CONTROLLER_TRIGGER_LAST_STOP;
+ }
+ writel(AST2600_I2CC_SET_RX_BUF_LEN(xfer_len), i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
+
+ return 0;
+}
+
+static int ast2600_i2c_setup_byte_rx(u32 cmd, struct ast2600_i2c_bus *i2c_bus)
+{
+ struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
+
+ cmd |= AST2600_I2CM_PKT_EN | AST2600_I2CM_RX_CMD;
+
+ if (cmd & AST2600_I2CM_START_CMD)
+ cmd |= AST2600_I2CM_PKT_ADDR(msg->addr);
+
+ if (msg->flags & I2C_M_RECV_LEN) {
+ dev_dbg(i2c_bus->dev, "smbus read\n");
+ } else if ((i2c_bus->msgs_index + 1 == i2c_bus->msgs_count) &&
+ ((i2c_bus->controller_xfer_cnt + 1) == msg->len)) {
+ cmd |= CONTROLLER_TRIGGER_LAST_STOP;
+ }
+
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
+
+ return 0;
+}
+
+static int ast2600_i2c_do_start(struct ast2600_i2c_bus *i2c_bus)
+{
+ struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
+
+ /* send start */
+ dev_dbg(i2c_bus->dev, "[%d] %s %d byte%s %s 0x%02x\n",
+ i2c_bus->msgs_index, str_read_write(msg->flags & I2C_M_RD),
+ msg->len, str_plural(msg->len),
+ msg->flags & I2C_M_RD ? "from" : "to", msg->addr);
+
+ if (!i2c_bus->setup_rx || !i2c_bus->setup_tx)
+ return -EINVAL;
+
+ i2c_bus->controller_xfer_cnt = 0;
+ i2c_bus->buf_index = 0;
+
+ if (msg->flags & I2C_M_RD)
+ return i2c_bus->setup_rx(AST2600_I2CM_START_CMD, i2c_bus);
+
+ return i2c_bus->setup_tx(AST2600_I2CM_START_CMD, i2c_bus);
+}
+
+static int ast2600_i2c_irq_err_to_errno(u32 irq_status)
+{
+ if (irq_status & AST2600_I2CM_ARBIT_LOSS)
+ return -EAGAIN;
+ if (irq_status & (AST2600_I2CM_SDA_DL_TO | AST2600_I2CM_SCL_LOW_TO))
+ return -ETIMEDOUT;
+ if (irq_status & (AST2600_I2CM_ABNORMAL))
+ return -EPROTO;
+
+ return 0;
+}
+
+static void ast2600_i2c_controller_packet_irq(struct ast2600_i2c_bus *i2c_bus, u32 sts)
+{
+ struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
+ int xfer_len;
+ int i;
+
+ sts &= ~AST2600_I2CM_PKT_DONE;
+ writel(AST2600_I2CM_PKT_DONE, i2c_bus->reg_base + AST2600_I2CM_ISR);
+ switch (sts) {
+ case AST2600_I2CM_PKT_ERROR:
+ i2c_bus->cmd_err = -EAGAIN;
+ complete(&i2c_bus->cmd_complete);
+ break;
+ case AST2600_I2CM_PKT_ERROR | AST2600_I2CM_TX_NAK: /* a0 fix for issue */
+ fallthrough;
+ case AST2600_I2CM_PKT_ERROR | AST2600_I2CM_TX_NAK | AST2600_I2CM_NORMAL_STOP:
+ i2c_bus->cmd_err = -ENXIO;
+ complete(&i2c_bus->cmd_complete);
+ break;
+ case AST2600_I2CM_NORMAL_STOP:
+ /* write 0 byte only have stop isr */
+ i2c_bus->msgs_index++;
+ if (i2c_bus->msgs_index < i2c_bus->msgs_count) {
+ if (ast2600_i2c_do_start(i2c_bus)) {
+ i2c_bus->cmd_err = -ENOMEM;
+ complete(&i2c_bus->cmd_complete);
+ }
+ } else {
+ i2c_bus->cmd_err = i2c_bus->msgs_index;
+ complete(&i2c_bus->cmd_complete);
+ }
+ break;
+ case AST2600_I2CM_TX_ACK:
+ case AST2600_I2CM_TX_ACK | AST2600_I2CM_NORMAL_STOP:
+ if (i2c_bus->mode == DMA_MODE)
+ xfer_len = AST2600_I2C_GET_TX_DMA_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CM_DMA_LEN_STS));
+ else if (i2c_bus->mode == BUFF_MODE)
+ xfer_len = AST2600_I2CC_GET_TX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ else
+ xfer_len = 1;
+
+ i2c_bus->controller_xfer_cnt += xfer_len;
+
+ if (i2c_bus->controller_xfer_cnt == msg->len) {
+ i2c_bus->msgs_index++;
+ if (i2c_bus->msgs_index == i2c_bus->msgs_count) {
+ i2c_bus->cmd_err = i2c_bus->msgs_index;
+ complete(&i2c_bus->cmd_complete);
+ } else {
+ if (ast2600_i2c_do_start(i2c_bus)) {
+ i2c_bus->cmd_err = -ENOMEM;
+ complete(&i2c_bus->cmd_complete);
+ }
+ }
+ } else {
+ i2c_bus->setup_tx(0, i2c_bus);
+ }
+ break;
+ case AST2600_I2CM_RX_DONE:
+ case AST2600_I2CM_RX_DONE | AST2600_I2CM_NORMAL_STOP:
+ /* do next rx */
+ if (i2c_bus->mode == DMA_MODE) {
+ xfer_len = AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CM_DMA_LEN_STS));
+ memcpy(&msg->buf[i2c_bus->controller_xfer_cnt],
+ i2c_bus->controller_dma_buf, xfer_len);
+ } else if (i2c_bus->mode == BUFF_MODE) {
+ xfer_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < xfer_len; i++)
+ msg->buf[i2c_bus->controller_xfer_cnt + i] =
+ readb(i2c_bus->buf_base + 0x10 + i);
+ } else {
+ xfer_len = 1;
+ msg->buf[i2c_bus->controller_xfer_cnt] =
+ AST2600_I2CC_GET_RX_BUFF(readl(i2c_bus->reg_base +
+ AST2600_I2CC_STS_AND_BUFF));
+ }
+
+ if (msg->flags & I2C_M_RECV_LEN) {
+ u8 recv_len = AST2600_I2CC_GET_RX_BUFF(readl(i2c_bus->reg_base
+ + AST2600_I2CC_STS_AND_BUFF));
+ msg->len = min_t(unsigned int, recv_len, I2C_SMBUS_BLOCK_MAX);
+ msg->len += ((msg->flags & I2C_CLIENT_PEC) ? 2 : 1);
+ msg->flags &= ~I2C_M_RECV_LEN;
+ if (!recv_len)
+ i2c_bus->controller_xfer_cnt = 0;
+ else
+ i2c_bus->controller_xfer_cnt = 1;
+ } else {
+ i2c_bus->controller_xfer_cnt += xfer_len;
+ }
+
+ if (i2c_bus->controller_xfer_cnt == msg->len) {
+ i2c_bus->msgs_index++;
+ if (i2c_bus->msgs_index == i2c_bus->msgs_count) {
+ i2c_bus->cmd_err = i2c_bus->msgs_index;
+ complete(&i2c_bus->cmd_complete);
+ } else {
+ if (ast2600_i2c_do_start(i2c_bus)) {
+ i2c_bus->cmd_err = -ENOMEM;
+ complete(&i2c_bus->cmd_complete);
+ }
+ }
+ } else {
+ i2c_bus->setup_rx(0, i2c_bus);
+ }
+ break;
+ default:
+ dev_dbg(i2c_bus->dev, "unhandled sts %x\n", sts);
+ break;
+ }
+}
+
+static int ast2600_i2c_controller_irq(struct ast2600_i2c_bus *i2c_bus)
+{
+ u32 sts = readl(i2c_bus->reg_base + AST2600_I2CM_ISR);
+ u32 ctrl;
+
+ sts &= ~AST2600_I2CM_SMBUS_ALERT;
+
+ if (sts & AST2600_I2CM_BUS_RECOVER_FAIL) {
+ writel(AST2600_I2CM_BUS_RECOVER_FAIL, i2c_bus->reg_base + AST2600_I2CM_ISR);
+ ctrl = readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ writel(0, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ writel(ctrl, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ i2c_bus->cmd_err = -EPROTO;
+ complete(&i2c_bus->cmd_complete);
+ return 1;
+ }
+
+ if (sts & AST2600_I2CM_BUS_RECOVER) {
+ writel(AST2600_I2CM_BUS_RECOVER, i2c_bus->reg_base + AST2600_I2CM_ISR);
+ i2c_bus->cmd_err = 0;
+ complete(&i2c_bus->cmd_complete);
+ return 1;
+ }
+
+ i2c_bus->cmd_err = ast2600_i2c_irq_err_to_errno(sts);
+ if (i2c_bus->cmd_err) {
+ writel(AST2600_I2CM_PKT_DONE, i2c_bus->reg_base + AST2600_I2CM_ISR);
+ complete(&i2c_bus->cmd_complete);
+ return 1;
+ }
+
+ if (sts & AST2600_I2CM_PKT_DONE) {
+ ast2600_i2c_controller_packet_irq(i2c_bus, sts);
+ return 1;
+ }
+
+ return 0;
+}
+
+static irqreturn_t ast2600_i2c_bus_irq(int irq, void *dev_id)
+{
+ struct ast2600_i2c_bus *i2c_bus = dev_id;
+
+ return IRQ_RETVAL(ast2600_i2c_controller_irq(i2c_bus));
+}
+
+static int ast2600_i2c_controller_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+ struct ast2600_i2c_bus *i2c_bus = i2c_get_adapdata(adap);
+ unsigned long timeout;
+ int ret;
+
+ if (!i2c_bus->multi_master &&
+ (readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF) & AST2600_I2CC_BUS_BUSY_STS)) {
+ ret = ast2600_i2c_recover_bus(i2c_bus);
+ if (ret)
+ return ret;
+ }
+
+ i2c_bus->cmd_err = 0;
+ i2c_bus->msgs = msgs;
+ i2c_bus->msgs_index = 0;
+ i2c_bus->msgs_count = num;
+ reinit_completion(&i2c_bus->cmd_complete);
+ ret = ast2600_i2c_do_start(i2c_bus);
+ if (ret)
+ goto controller_out;
+ timeout = wait_for_completion_timeout(&i2c_bus->cmd_complete, i2c_bus->adap.timeout);
+ if (timeout == 0) {
+ u32 ctrl = readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+
+ dev_dbg(i2c_bus->dev, "timeout isr[%x], sts[%x]\n",
+ readl(i2c_bus->reg_base + AST2600_I2CM_ISR),
+ readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
+ writel(ctrl & ~AST2600_I2CC_MASTER_EN, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ writel(ctrl, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+
+ /*
+ * A slave holding SCL low can stall the transfer and trigger
+ * a master timeout. In multi-master mode, attempt bus recovery
+ * if the bus is still busy.
+ */
+ if (i2c_bus->multi_master &&
+ (readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF) &
+ AST2600_I2CC_BUS_BUSY_STS))
+ ast2600_i2c_recover_bus(i2c_bus);
+ ret = -ETIMEDOUT;
+ } else {
+ ret = i2c_bus->cmd_err;
+ }
+
+ dev_dbg(i2c_bus->dev, "bus%d-m: %d end\n", i2c_bus->adap.nr, i2c_bus->cmd_err);
+
+controller_out:
+ return ret;
+}
+
+static int ast2600_i2c_init(struct ast2600_i2c_bus *i2c_bus)
+{
+ u32 fun_ctrl = AST2600_I2CC_BUS_AUTO_RELEASE | AST2600_I2CC_MASTER_EN;
+
+ /* I2C Reset */
+ writel(0, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+
+ if (!i2c_bus->multi_master)
+ fun_ctrl |= AST2600_I2CC_MULTI_MASTER_DIS;
+
+ /* Enable Controller Mode */
+ writel(fun_ctrl, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ /* disable target address */
+ writel(0, i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
+
+ /* Set AC Timing */
+ ast2600_i2c_ac_timing_config(i2c_bus);
+
+ if (i2c_bus->mode == DMA_MODE) {
+ i2c_bus->controller_dma_buf =
+ dmam_alloc_coherent(i2c_bus->dev, AST2600_I2C_DMA_SIZE,
+ &i2c_bus->controller_dma_addr, GFP_KERNEL);
+ if (!i2c_bus->controller_dma_buf)
+ return -ENOMEM;
+ writel(i2c_bus->controller_dma_addr,
+ i2c_bus->reg_base + AST2600_I2CM_TX_DMA);
+ writel(i2c_bus->controller_dma_addr,
+ i2c_bus->reg_base + AST2600_I2CM_RX_DMA);
+ }
+
+ /* Clear Interrupt */
+ writel(GENMASK(27, 0), i2c_bus->reg_base + AST2600_I2CM_ISR);
+
+ return 0;
+}
+
+static u32 ast2600_i2c_functionality(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
+}
+
+static const struct i2c_algorithm i2c_ast2600_algorithm = {
+ .xfer = ast2600_i2c_controller_xfer,
+ .functionality = ast2600_i2c_functionality,
+};
+
+static int ast2600_i2c_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct ast2600_i2c_bus *i2c_bus;
+ struct reset_control *rst;
+ const char *xfer_mode;
+ struct resource *res;
+ u32 global_ctrl;
+ int ret;
+
+ if (!device_property_present(dev, "aspeed,global-regs"))
+ return -ENODEV;
+
+ i2c_bus = devm_kzalloc(dev, sizeof(*i2c_bus), GFP_KERNEL);
+ if (!i2c_bus)
+ return -ENOMEM;
+
+ i2c_bus->reg_base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(i2c_bus->reg_base))
+ return PTR_ERR(i2c_bus->reg_base);
+
+ rst = devm_reset_control_get_shared_deasserted(dev, NULL);
+ if (IS_ERR(rst))
+ return dev_err_probe(dev, PTR_ERR(rst), "Missing reset ctrl\n");
+
+ i2c_bus->global_regs =
+ syscon_regmap_lookup_by_phandle(dev_of_node(dev), "aspeed,global-regs");
+ if (IS_ERR(i2c_bus->global_regs))
+ return PTR_ERR(i2c_bus->global_regs);
+
+ regmap_read(i2c_bus->global_regs, AST2600_I2CG_CTRL, &global_ctrl);
+ if ((global_ctrl & AST2600_GLOBAL_INIT) != AST2600_GLOBAL_INIT) {
+ regmap_write(i2c_bus->global_regs, AST2600_I2CG_CTRL, AST2600_GLOBAL_INIT);
+ regmap_write(i2c_bus->global_regs, AST2600_I2CG_CLK_DIV_CTRL, I2CCG_DIV_CTRL);
+ }
+
+ i2c_bus->dev = dev;
+ i2c_bus->multi_master = device_property_read_bool(dev, "multi-master");
+ i2c_bus->mode = BUFF_MODE;
+ if (!device_property_read_string(dev, "aspeed,transfer-mode", &xfer_mode)) {
+ if (!strcmp(xfer_mode, "dma"))
+ i2c_bus->mode = DMA_MODE;
+ else if (!strcmp(xfer_mode, "byte"))
+ i2c_bus->mode = BYTE_MODE;
+ else
+ i2c_bus->mode = BUFF_MODE;
+ }
+
+ if (i2c_bus->mode == BUFF_MODE) {
+ i2c_bus->buf_base = devm_platform_get_and_ioremap_resource(pdev, 1, &res);
+ if (IS_ERR(i2c_bus->buf_base))
+ i2c_bus->mode = BYTE_MODE;
+ else
+ i2c_bus->buf_size = resource_size(res) / 2;
+ }
+
+ switch (i2c_bus->mode) {
+ case DMA_MODE:
+ i2c_bus->setup_tx = ast2600_i2c_setup_dma_tx;
+ i2c_bus->setup_rx = ast2600_i2c_setup_dma_rx;
+ break;
+ case BUFF_MODE:
+ default:
+ i2c_bus->setup_tx = ast2600_i2c_setup_buff_tx;
+ i2c_bus->setup_rx = ast2600_i2c_setup_buff_rx;
+ break;
+ case BYTE_MODE:
+ i2c_bus->setup_tx = ast2600_i2c_setup_byte_tx;
+ i2c_bus->setup_rx = ast2600_i2c_setup_byte_rx;
+ break;
+ }
+
+ /*
+ * i2c timeout counter: use base clk4 1Mhz,
+ * per unit: 1/(1000/1024) = 1024us
+ */
+ ret = device_property_read_u32(dev, "i2c-scl-clk-low-timeout-us", &i2c_bus->timeout);
+ if (!ret)
+ i2c_bus->timeout = DIV_ROUND_UP(i2c_bus->timeout, 1024);
+
+ init_completion(&i2c_bus->cmd_complete);
+
+ i2c_bus->irq = platform_get_irq(pdev, 0);
+ if (i2c_bus->irq < 0)
+ return i2c_bus->irq;
+
+ platform_set_drvdata(pdev, i2c_bus);
+
+ i2c_bus->clk = devm_clk_get(i2c_bus->dev, NULL);
+ if (IS_ERR(i2c_bus->clk))
+ return dev_err_probe(i2c_bus->dev, PTR_ERR(i2c_bus->clk), "Can't get clock\n");
+
+ i2c_bus->apb_clk = clk_get_rate(i2c_bus->clk);
+
+ i2c_parse_fw_timings(i2c_bus->dev, &i2c_bus->timing_info, true);
+
+ /* Initialize the I2C adapter */
+ i2c_bus->adap.owner = THIS_MODULE;
+ i2c_bus->adap.algo = &i2c_ast2600_algorithm;
+ i2c_bus->adap.retries = 0;
+ i2c_bus->adap.dev.parent = i2c_bus->dev;
+ device_set_node(&i2c_bus->adap.dev, dev_fwnode(dev));
+ i2c_bus->adap.algo_data = i2c_bus;
+ strscpy(i2c_bus->adap.name, pdev->name);
+ i2c_set_adapdata(&i2c_bus->adap, i2c_bus);
+
+ ret = ast2600_i2c_init(i2c_bus);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "Unable to initial i2c %d\n", ret);
+
+ ret = devm_request_irq(dev, i2c_bus->irq, ast2600_i2c_bus_irq, 0,
+ dev_name(dev), i2c_bus);
+ if (ret < 0) {
+ ret = dev_err_probe(dev, ret, "Unable to request irq %d\n",
+ i2c_bus->irq);
+ goto err;
+ }
+
+ writel(AST2600_I2CM_PKT_DONE | AST2600_I2CM_BUS_RECOVER,
+ i2c_bus->reg_base + AST2600_I2CM_IER);
+
+ ret = devm_i2c_add_adapter(dev, &i2c_bus->adap);
+ if (ret)
+ goto err;
+
+ return 0;
+
+err:
+ writel(0, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ writel(0, i2c_bus->reg_base + AST2600_I2CM_IER);
+ return ret;
+}
+
+static void ast2600_i2c_remove(struct platform_device *pdev)
+{
+ struct ast2600_i2c_bus *i2c_bus = platform_get_drvdata(pdev);
+
+ /* Disable everything. */
+ writel(0, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ writel(0, i2c_bus->reg_base + AST2600_I2CM_IER);
+}
+
+static const struct of_device_id ast2600_i2c_of_match[] = {
+ { .compatible = "aspeed,ast2600-i2c-bus" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ast2600_i2c_of_match);
+
+static struct platform_driver ast2600_i2c_driver = {
+ .probe = ast2600_i2c_probe,
+ .remove = ast2600_i2c_remove,
+ .driver = {
+ .name = "ast2600-i2c",
+ .of_match_table = ast2600_i2c_of_match,
+ },
+};
+module_platform_driver(ast2600_i2c_driver);
+
+MODULE_AUTHOR("Ryan Chen <ryan_chen@aspeedtech.com>");
+MODULE_DESCRIPTION("ASPEED AST2600 I2C Controller Driver");
+MODULE_LICENSE("GPL");
--
2.34.1
^ permalink raw reply related [flat|nested] 18+ messages in thread
* [PATCH v26 4/4] i2c: ast2600: Add target mode support
2026-03-09 6:53 [PATCH v26 0/4] Add ASPEED AST2600 I2C controller driver Ryan Chen
` (2 preceding siblings ...)
2026-03-09 6:53 ` [PATCH v26 3/4] i2c: ast2600: Add controller driver for AST2600 new register set Ryan Chen
@ 2026-03-09 6:53 ` Ryan Chen
3 siblings, 0 replies; 18+ messages in thread
From: Ryan Chen @ 2026-03-09 6:53 UTC (permalink / raw)
To: jk, andriy.shevchenko, Andi Shyti, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Rayn Chen, Philipp Zabel
Cc: linux-i2c, devicetree, linux-arm-kernel, linux-aspeed,
linux-kernel, openbmc, Ryan Chen
Add target mode support to the AST2600 I2C driver.
Target mode features implemented include:
- Add target interrupt handling
- Address match and response logic
- Separate Tx/Rx DMA address and length configuration
This complements the existing controller-mode support, enabling
dual-role capability.
Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
---
Changes in v26:
- change int to bool target_operate
- rename target_operate to target_active
- use i2c_bus->target replace require IO
- use WRITE_ONCE replace target_operate write.
---
drivers/i2c/busses/i2c-ast2600.c | 565 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 564 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-ast2600.c b/drivers/i2c/busses/i2c-ast2600.c
index c3e4abb426e2..5cb8bedbaad9 100644
--- a/drivers/i2c/busses/i2c-ast2600.c
+++ b/drivers/i2c/busses/i2c-ast2600.c
@@ -273,6 +273,13 @@ struct ast2600_i2c_bus {
void __iomem *buf_base;
int (*setup_tx)(u32 cmd, struct ast2600_i2c_bus *i2c_bus);
int (*setup_rx)(u32 cmd, struct ast2600_i2c_bus *i2c_bus);
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /* target structure */
+ bool target_active;
+ unsigned char *target_dma_buf;
+ dma_addr_t target_dma_addr;
+ struct i2c_client *target;
+#endif
};
static void ast2600_i2c_ac_timing_config(struct ast2600_i2c_bus *i2c_bus)
@@ -356,6 +363,440 @@ static int ast2600_i2c_recover_bus(struct ast2600_i2c_bus *i2c_bus)
return ret;
}
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static void ast2600_i2c_target_packet_dma_irq(struct ast2600_i2c_bus *i2c_bus, u32 sts)
+{
+ int target_rx_len = 0;
+ u32 cmd = 0;
+ u8 value;
+ int i;
+
+ sts &= ~(AST2600_I2CS_SLAVE_PENDING);
+ /* Handle i2c target timeout condition */
+ if (sts & AST2600_I2CS_INACTIVE_TO) {
+ /* Reset timeout counter */
+ u32 ac_timing = readl(i2c_bus->reg_base + AST2600_I2CC_AC_TIMING) &
+ AST2600_I2CC_AC_TIMING_MASK;
+
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ ac_timing |= AST2600_I2CC_TTIMEOUT(i2c_bus->timeout);
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ return;
+ }
+
+ sts &= ~(AST2600_I2CS_PKT_DONE | AST2600_I2CS_PKT_ERROR);
+
+ switch (sts) {
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_RX_DMA:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ target_rx_len = AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CS_DMA_LEN_STS));
+ for (i = 0; i < target_rx_len; i++) {
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED,
+ &i2c_bus->target_dma_buf[i]);
+ }
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_STOP:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE_NAK |
+ AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_RX_DMA |
+ AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_RX_DONE_NAK | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_STOP:
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ if (sts & AST2600_I2CS_SLAVE_MATCH)
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+
+ target_rx_len = AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CS_DMA_LEN_STS));
+ for (i = 0; i < target_rx_len; i++) {
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED,
+ &i2c_bus->target_dma_buf[i]);
+ }
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ if (sts & AST2600_I2CS_STOP)
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ break;
+
+ /* it is Mw data Mr coming -> it need send tx */
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_TX_DMA:
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_TX_DMA:
+ /* it should be repeat start read */
+ if (sts & AST2600_I2CS_SLAVE_MATCH)
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+
+ target_rx_len = AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CS_DMA_LEN_STS));
+ for (i = 0; i < target_rx_len; i++) {
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED,
+ &i2c_bus->target_dma_buf[i]);
+ }
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED,
+ &i2c_bus->target_dma_buf[0]);
+ writel(AST2600_I2CS_SET_TX_DMA_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_DMA_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_TX_DMA:
+ /* First Start read */
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED,
+ &i2c_bus->target_dma_buf[0]);
+ writel(AST2600_I2CS_SET_TX_DMA_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_DMA_EN;
+ break;
+ case AST2600_I2CS_WAIT_TX_DMA:
+ /* it should be next start read */
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_PROCESSED,
+ &i2c_bus->target_dma_buf[0]);
+ writel(AST2600_I2CS_SET_TX_DMA_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_DMA_EN;
+ break;
+ case AST2600_I2CS_TX_NAK | AST2600_I2CS_STOP:
+ /* it just tx complete */
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ break;
+ case AST2600_I2CS_STOP:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ default:
+ dev_dbg(i2c_bus->dev, "unhandled target isr case %x, sts %x\n", sts,
+ readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
+ break;
+ }
+
+ if (cmd)
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+}
+
+static void ast2600_i2c_target_packet_buff_irq(struct ast2600_i2c_bus *i2c_bus, u32 sts)
+{
+ int target_rx_len = 0;
+ u32 cmd = 0;
+ u8 value;
+ int i;
+
+ /* due to controller target is common buffer, need force the master stop not issue */
+ if (readl(i2c_bus->reg_base + AST2600_I2CM_CMD_STS) & GENMASK(15, 0)) {
+ writel(0, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
+ i2c_bus->cmd_err = -EBUSY;
+ writel(0, i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ complete(&i2c_bus->cmd_complete);
+ }
+
+ /* Handle i2c target timeout condition */
+ if (AST2600_I2CS_INACTIVE_TO & sts) {
+ /* Reset timeout counter */
+ u32 ac_timing = readl(i2c_bus->reg_base + AST2600_I2CC_AC_TIMING) &
+ AST2600_I2CC_AC_TIMING_MASK;
+
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ ac_timing |= AST2600_I2CC_TTIMEOUT(i2c_bus->timeout);
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ writel(TARGET_TRIGGER_CMD, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ WRITE_ONCE(i2c_bus->target_active, false);
+ return;
+ }
+
+ sts &= ~(AST2600_I2CS_PKT_DONE | AST2600_I2CS_PKT_ERROR);
+
+ if (sts & AST2600_I2CS_SLAVE_MATCH)
+ WRITE_ONCE(i2c_bus->target_active, true);
+
+ switch (sts) {
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_WAIT_RX_DMA |
+ AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_SLAVE_PENDING |
+ AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_SLAVE_PENDING |
+ AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_STOP:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ fallthrough;
+ case AST2600_I2CS_SLAVE_PENDING |
+ AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_SLAVE_MATCH:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ cmd = TARGET_TRIGGER_CMD;
+ if (sts & AST2600_I2CS_RX_DONE) {
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ }
+ if (readl(i2c_bus->reg_base + AST2600_I2CS_CMD_STS) & AST2600_I2CS_RX_BUFF_EN)
+ cmd = 0;
+ else
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_BUFF_EN;
+
+ writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ break;
+ case AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_RX_DONE:
+ cmd = TARGET_TRIGGER_CMD;
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ cmd |= AST2600_I2CS_RX_BUFF_EN;
+ writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ break;
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_WAIT_RX_DMA |
+ AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ cmd = TARGET_TRIGGER_CMD;
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ cmd |= AST2600_I2CS_RX_BUFF_EN;
+ writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ break;
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ cmd = TARGET_TRIGGER_CMD;
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ /* workaround for avoid next start with len != 0 */
+ writel(BIT(0), i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ cmd = TARGET_TRIGGER_CMD;
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ /* workaround for avoid next start with len != 0 */
+ writel(BIT(0), i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_RX_DONE |
+ AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_STOP:
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED, &value);
+ writeb(value, i2c_bus->buf_base);
+ break;
+ case AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_SLAVE_MATCH:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED, &value);
+ writeb(value, i2c_bus->buf_base);
+ writel(AST2600_I2CC_SET_TX_BUF_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_BUFF_EN;
+ break;
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_STOP |
+ AST2600_I2CS_TX_NAK | AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_STOP |
+ AST2600_I2CS_TX_NAK | AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_BUFF_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_WAIT_TX_DMA:
+ if (sts & AST2600_I2CS_SLAVE_MATCH)
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+
+ if (sts & AST2600_I2CS_RX_DONE) {
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED, &value);
+ } else {
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_PROCESSED, &value);
+ }
+ writeb(value, i2c_bus->buf_base);
+ writel(AST2600_I2CC_SET_TX_BUF_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_BUFF_EN;
+ break;
+ /* workaround : trigger the cmd twice to fix next state keep 1000000 */
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_BUFF_EN;
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ break;
+ case AST2600_I2CS_TX_NAK | AST2600_I2CS_STOP:
+ case AST2600_I2CS_STOP:
+ cmd = TARGET_TRIGGER_CMD;
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ default:
+ dev_dbg(i2c_bus->dev, "unhandled target isr case %x, sts %x\n", sts,
+ readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
+ break;
+ }
+
+ if (cmd)
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+
+ if ((sts & AST2600_I2CS_STOP) && !(sts & AST2600_I2CS_SLAVE_PENDING))
+ WRITE_ONCE(i2c_bus->target_active, false);
+}
+
+static void ast2600_i2c_target_byte_irq(struct ast2600_i2c_bus *i2c_bus, u32 sts)
+{
+ u32 i2c_buff = readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ u32 cmd = AST2600_I2CS_ACTIVE_ALL;
+ u8 byte_data;
+ u8 value;
+
+ /* Handle i2c target timeout condition */
+ if (sts & AST2600_I2CS_INACTIVE_TO) {
+ /* Reset timeout counter */
+ u32 ac_timing = readl(i2c_bus->reg_base + AST2600_I2CC_AC_TIMING) &
+ AST2600_I2CC_AC_TIMING_MASK;
+
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ ac_timing |= AST2600_I2CC_TTIMEOUT(i2c_bus->timeout);
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ writel(AST2600_I2CS_ACTIVE_ALL, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(sts, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ WRITE_ONCE(i2c_bus->target_active, false);
+ return;
+ }
+
+ switch (sts) {
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ /* first address match is address */
+ byte_data = AST2600_I2CC_GET_RX_BUFF(i2c_buff);
+ break;
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
+ byte_data = AST2600_I2CC_GET_RX_BUFF(i2c_buff);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &byte_data);
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_TX_DMA:
+ cmd |= AST2600_I2CS_TX_CMD;
+ byte_data = AST2600_I2CC_GET_RX_BUFF(i2c_buff);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED, &byte_data);
+ writel(byte_data, i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ break;
+ case AST2600_I2CS_TX_ACK | AST2600_I2CS_WAIT_TX_DMA:
+ cmd |= AST2600_I2CS_TX_CMD;
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_PROCESSED, &byte_data);
+ writel(byte_data, i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ break;
+ case AST2600_I2CS_STOP:
+ case AST2600_I2CS_STOP | AST2600_I2CS_TX_NAK:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ default:
+ dev_dbg(i2c_bus->dev, "unhandled pkt isr %x\n", sts);
+ break;
+ }
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(sts, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+}
+
+static int ast2600_i2c_target_irq(struct ast2600_i2c_bus *i2c_bus)
+{
+ u32 ier = readl(i2c_bus->reg_base + AST2600_I2CS_IER);
+ u32 isr = readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+
+ if (!(isr & ier))
+ return 0;
+
+ /*
+ * Target interrupt coming after controller packet done
+ * So need handle controller first.
+ */
+ if (readl(i2c_bus->reg_base + AST2600_I2CM_ISR) & AST2600_I2CM_PKT_DONE)
+ return 0;
+
+ isr &= ~(AST2600_I2CS_ADDR_INDICATE_MASK);
+
+ if (AST2600_I2CS_ADDR1_NAK & isr)
+ isr &= ~AST2600_I2CS_ADDR1_NAK;
+
+ if (AST2600_I2CS_ADDR2_NAK & isr)
+ isr &= ~AST2600_I2CS_ADDR2_NAK;
+
+ if (AST2600_I2CS_ADDR3_NAK & isr)
+ isr &= ~AST2600_I2CS_ADDR3_NAK;
+
+ if (AST2600_I2CS_ADDR_MASK & isr)
+ isr &= ~AST2600_I2CS_ADDR_MASK;
+
+ if (AST2600_I2CS_PKT_DONE & isr) {
+ if (i2c_bus->mode == DMA_MODE)
+ ast2600_i2c_target_packet_dma_irq(i2c_bus, isr);
+ else
+ ast2600_i2c_target_packet_buff_irq(i2c_bus, isr);
+ } else {
+ ast2600_i2c_target_byte_irq(i2c_bus, isr);
+ }
+
+ return 1;
+}
+#endif
+
static int ast2600_i2c_setup_dma_tx(u32 cmd, struct ast2600_i2c_bus *i2c_bus)
{
struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
@@ -627,6 +1068,20 @@ static void ast2600_i2c_controller_packet_irq(struct ast2600_i2c_bus *i2c_bus, u
}
break;
case AST2600_I2CM_RX_DONE:
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /*
+ * Workaround for controller/target packet mode enable rx done stuck issue
+ * When controller go for first read (RX_DONE), target mode will also effect
+ * Then controller will send nack, not operate anymore.
+ */
+ if (readl(i2c_bus->reg_base + AST2600_I2CS_CMD_STS) & AST2600_I2CS_PKT_MODE_EN) {
+ u32 target_cmd = readl(i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+
+ writel(0, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(target_cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ }
+ fallthrough;
+#endif
case AST2600_I2CM_RX_DONE | AST2600_I2CM_NORMAL_STOP:
/* do next rx */
if (i2c_bus->mode == DMA_MODE) {
@@ -725,6 +1180,12 @@ static irqreturn_t ast2600_i2c_bus_irq(int irq, void *dev_id)
{
struct ast2600_i2c_bus *i2c_bus = dev_id;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (i2c_bus->target) {
+ if (ast2600_i2c_target_irq(i2c_bus))
+ return IRQ_HANDLED;
+ }
+#endif
return IRQ_RETVAL(ast2600_i2c_controller_irq(i2c_bus));
}
@@ -741,12 +1202,35 @@ static int ast2600_i2c_controller_xfer(struct i2c_adapter *adap, struct i2c_msg
return ret;
}
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (i2c_bus->mode == BUFF_MODE) {
+ if (i2c_bus->target_active)
+ return -EBUSY;
+ /**
+ * In BUFF_MODE, controller and target share the same buffer register,
+ * A target transaction can update buffer state asynchronously via IRQ,
+ * so block controller transfers while target is active, otherwise we can
+ * corrupt buffer.
+ */
+ writel(0, i2c_bus->reg_base + AST2600_I2CS_IER);
+ if (readl(i2c_bus->reg_base + AST2600_I2CS_ISR) || i2c_bus->target_active) {
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_IER);
+ return -EBUSY;
+ }
+ }
+#endif
+
i2c_bus->cmd_err = 0;
i2c_bus->msgs = msgs;
i2c_bus->msgs_index = 0;
i2c_bus->msgs_count = num;
reinit_completion(&i2c_bus->cmd_complete);
ret = ast2600_i2c_do_start(i2c_bus);
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /* avoid race condication target is wait and controller wait 1st target operate */
+ if (i2c_bus->mode == BUFF_MODE)
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_IER);
+#endif
if (ret)
goto controller_out;
timeout = wait_for_completion_timeout(&i2c_bus->cmd_complete, i2c_bus->adap.timeout);
@@ -764,7 +1248,7 @@ static int ast2600_i2c_controller_xfer(struct i2c_adapter *adap, struct i2c_msg
* a master timeout. In multi-master mode, attempt bus recovery
* if the bus is still busy.
*/
- if (i2c_bus->multi_master &&
+ if (i2c_bus->multi_master && !i2c_bus->target_active &&
(readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF) &
AST2600_I2CC_BUS_BUSY_STS))
ast2600_i2c_recover_bus(i2c_bus);
@@ -812,8 +1296,80 @@ static int ast2600_i2c_init(struct ast2600_i2c_bus *i2c_bus)
/* Clear Interrupt */
writel(GENMASK(27, 0), i2c_bus->reg_base + AST2600_I2CM_ISR);
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /* for memory buffer initial */
+ if (i2c_bus->mode == DMA_MODE) {
+ i2c_bus->target_dma_buf =
+ dmam_alloc_coherent(i2c_bus->dev, I2C_TARGET_MSG_BUF_SIZE,
+ &i2c_bus->target_dma_addr, GFP_KERNEL);
+ if (!i2c_bus->target_dma_buf)
+ return -ENOMEM;
+ }
+
+ writel(GENMASK(27, 0), i2c_bus->reg_base + AST2600_I2CS_ISR);
+
+ if (i2c_bus->mode == BYTE_MODE)
+ writel(GENMASK(15, 0), i2c_bus->reg_base + AST2600_I2CS_IER);
+ else
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_IER);
+#endif
+
+ return 0;
+}
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static int ast2600_i2c_reg_target(struct i2c_client *client)
+{
+ struct ast2600_i2c_bus *i2c_bus = i2c_get_adapdata(client->adapter);
+ u32 cmd = TARGET_TRIGGER_CMD;
+
+ if (i2c_bus->target)
+ return -EINVAL;
+
+ dev_dbg(i2c_bus->dev, "target addr %x\n", client->addr);
+
+ writel(0, i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
+ writel(AST2600_I2CC_SLAVE_EN | readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL),
+ i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+
+ /* trigger rx buffer */
+ if (i2c_bus->mode == DMA_MODE) {
+ cmd |= AST2600_I2CS_RX_DMA_EN;
+ writel(i2c_bus->target_dma_addr, i2c_bus->reg_base + AST2600_I2CS_RX_DMA);
+ writel(i2c_bus->target_dma_addr, i2c_bus->reg_base + AST2600_I2CS_TX_DMA);
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ } else if (i2c_bus->mode == BUFF_MODE) {
+ cmd = TARGET_TRIGGER_CMD;
+ } else {
+ cmd &= ~AST2600_I2CS_PKT_MODE_EN;
+ }
+
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ i2c_bus->target = client;
+ /* Set target addr. */
+ writel(client->addr | AST2600_I2CS_ADDR1_ENABLE,
+ i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
+
+ return 0;
+}
+
+static int ast2600_i2c_unreg_target(struct i2c_client *client)
+{
+ struct ast2600_i2c_bus *i2c_bus = i2c_get_adapdata(client->adapter);
+ u32 val;
+
+ /* Turn off target mode. */
+ val = readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ writel(val & ~AST2600_I2CC_SLAVE_EN, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ val = readl(i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
+ writel(val & ~AST2600_I2CS_ADDR1_MASK, i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
+
+ i2c_bus->target = NULL;
+
return 0;
}
+#endif
static u32 ast2600_i2c_functionality(struct i2c_adapter *adap)
{
@@ -823,6 +1379,10 @@ static u32 ast2600_i2c_functionality(struct i2c_adapter *adap)
static const struct i2c_algorithm i2c_ast2600_algorithm = {
.xfer = ast2600_i2c_controller_xfer,
.functionality = ast2600_i2c_functionality,
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ .reg_target = ast2600_i2c_reg_target,
+ .unreg_target = ast2600_i2c_unreg_target,
+#endif
};
static int ast2600_i2c_probe(struct platform_device *pdev)
@@ -861,6 +1421,9 @@ static int ast2600_i2c_probe(struct platform_device *pdev)
regmap_write(i2c_bus->global_regs, AST2600_I2CG_CLK_DIV_CTRL, I2CCG_DIV_CTRL);
}
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ WRITE_ONCE(i2c_bus->target_active, false);
+#endif
i2c_bus->dev = dev;
i2c_bus->multi_master = device_property_read_bool(dev, "multi-master");
i2c_bus->mode = BUFF_MODE;
--
2.34.1
^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-09 6:53 ` [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties Ryan Chen
@ 2026-03-13 23:21 ` Rob Herring
2026-03-14 0:24 ` Ryan Chen
0 siblings, 1 reply; 18+ messages in thread
From: Rob Herring @ 2026-03-13 23:21 UTC (permalink / raw)
To: Ryan Chen
Cc: jk, andriy.shevchenko, Andi Shyti, Krzysztof Kozlowski,
Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Rayn Chen, Philipp Zabel, linux-i2c,
devicetree, linux-arm-kernel, linux-aspeed, linux-kernel, openbmc
On Mon, Mar 09, 2026 at 02:53:53PM +0800, Ryan Chen wrote:
> The AST2600 I2C controller supports three transfer modes (byte, buffer,
> DMA). Add "aspeed,transfer-mode" so DT can select the preferred transfer
> method per controller instance. Also add the "aspeed,global-regs"
> phandle to reference the AST2600 global registers syscon/regmap used by
> the controller.
>
> These properties apply only to the AST2600 binding and are not part of
> the legacy binding, which uses a mixed controller/target register layout
> and does not have the split register blocks or these new configuration
> registers. Legacy DTs remain unchanged.
>
> Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
> ---
> .../bindings/i2c/aspeed,ast2600-i2c.yaml | 29 ++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> index de2c359037da..323e4f9b290a 100644
> --- a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> +++ b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> @@ -37,6 +37,33 @@ properties:
> resets:
> maxItems: 1
>
> + aspeed,transfer-mode:
> + description: |
> + ASPEED ast2600 platform equipped with 16 I2C controllers each i2c controller
> + have 1 byte transfer buffer(byte mode), 32 bytes buffer(buffer mode), and
> + share a DMA engine.
> + Select I2C transfer mode for this controller. Supported values are:
> + - "byte": Use 1 byte for i2c transmit (1-byte buffer).
> + - "buffer": Use buffer (32-byte buffer) for i2c transmit. (default)
> + Better performance then byte mode.
Good, I like worse performance so I can use byte mode.
> + - "dma": Each controller DMA mode is shared DMA engine. The AST2600 SoC
> + provides a single DMA engine shared for 16 I2C controllers,
> + so only a limited number of controllers can use DMA simultaneously.
> + Therefore, the DTS must explicitly assign which controllers are
> + configured to use DMA.
> + On AST2600, each controller supports all three modes.
> + If not specified, buffer mode is used by default.
> + enum:
> + - byte
> + - buffer
> + - dma
This is not required, so what is the default mode? If there's a default,
you don't need the default value in the first place as the default is
the property omitted.
> +
> + aspeed,global-regs:
> + $ref: /schemas/types.yaml#/definitions/phandle
> + description:
> + Phandle reference to the i2c global syscon node, containing the
> + SoC-common i2c register set.
> +
> required:
> - reg
> - compatible
> @@ -59,4 +86,6 @@ examples:
> resets = <&syscon ASPEED_RESET_I2C>;
> clock-frequency = <100000>;
> interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
> + aspeed,global-regs = <&i2c_global>;
> + aspeed,transfer-mode = "buffer";
> };
>
> --
> 2.34.1
>
^ permalink raw reply [flat|nested] 18+ messages in thread
* RE: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-13 23:21 ` Rob Herring
@ 2026-03-14 0:24 ` Ryan Chen
2026-03-16 1:49 ` Jeremy Kerr
0 siblings, 1 reply; 18+ messages in thread
From: Ryan Chen @ 2026-03-14 0:24 UTC (permalink / raw)
To: Rob Herring
Cc: jk@codeconstruct.com.au, andriy.shevchenko@linux.intel.com,
Andi Shyti, Krzysztof Kozlowski, Conor Dooley, Joel Stanley,
Andrew Jeffery, Benjamin Herrenschmidt, Philipp Zabel,
linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
> Subject: Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs
> and transfer-mode properties
>
> On Mon, Mar 09, 2026 at 02:53:53PM +0800, Ryan Chen wrote:
> > The AST2600 I2C controller supports three transfer modes (byte,
> > buffer, DMA). Add "aspeed,transfer-mode" so DT can select the
> > preferred transfer method per controller instance. Also add the
> "aspeed,global-regs"
> > phandle to reference the AST2600 global registers syscon/regmap used
> > by the controller.
> >
> > These properties apply only to the AST2600 binding and are not part of
> > the legacy binding, which uses a mixed controller/target register
> > layout and does not have the split register blocks or these new
> > configuration registers. Legacy DTs remain unchanged.
> >
> > Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
> > ---
> > .../bindings/i2c/aspeed,ast2600-i2c.yaml | 29
> ++++++++++++++++++++++
> > 1 file changed, 29 insertions(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> > b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> > index de2c359037da..323e4f9b290a 100644
> > --- a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> > +++ b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> > @@ -37,6 +37,33 @@ properties:
> > resets:
> > maxItems: 1
> >
> > + aspeed,transfer-mode:
> > + description: |
> > + ASPEED ast2600 platform equipped with 16 I2C controllers each i2c
> controller
> > + have 1 byte transfer buffer(byte mode), 32 bytes buffer(buffer mode),
> and
> > + share a DMA engine.
> > + Select I2C transfer mode for this controller. Supported values are:
> > + - "byte": Use 1 byte for i2c transmit (1-byte buffer).
> > + - "buffer": Use buffer (32-byte buffer) for i2c transmit. (default)
> > + Better performance then byte mode.
>
> Good, I like worse performance so I can use byte mode.
Thanks your review.
Will remove performance statement.
>
> > + - "dma": Each controller DMA mode is shared DMA engine. The
> AST2600 SoC
> > + provides a single DMA engine shared for 16 I2C
> controllers,
> > + so only a limited number of controllers can use DMA
> simultaneously.
> > + Therefore, the DTS must explicitly assign which
> controllers are
> > + configured to use DMA.
> > + On AST2600, each controller supports all three modes.
> > + If not specified, buffer mode is used by default.
> > + enum:
> > + - byte
> > + - buffer
> > + - dma
>
> This is not required, so what is the default mode? If there's a default, you don't
> need the default value in the first place as the default is the property omitted.
Thanks, Will update with following.
aspeed,transfer-mode:
description:
Selects the AST2600 I2C transfer mode:
- byte: 1-byte transfer buffer
- buffer: 32-byte transfer buffer
- dma: DMA-based transfers
enum:
- byte
- buffer
- dma
>
> > +
> > + aspeed,global-regs:
> > + $ref: /schemas/types.yaml#/definitions/phandle
> > + description:
> > + Phandle reference to the i2c global syscon node, containing the
> > + SoC-common i2c register set.
> > +
> > required:
> > - reg
> > - compatible
> > @@ -59,4 +86,6 @@ examples:
> > resets = <&syscon ASPEED_RESET_I2C>;
> > clock-frequency = <100000>;
> > interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
> > + aspeed,global-regs = <&i2c_global>;
> > + aspeed,transfer-mode = "buffer";
> > };
> >
> > --
> > 2.34.1
> >
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-14 0:24 ` Ryan Chen
@ 2026-03-16 1:49 ` Jeremy Kerr
2026-03-16 16:47 ` Rob Herring
0 siblings, 1 reply; 18+ messages in thread
From: Jeremy Kerr @ 2026-03-16 1:49 UTC (permalink / raw)
To: Ryan Chen, Rob Herring
Cc: andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
Hi Ryan & Rob,
> > > + aspeed,transfer-mode:
> > > + description: |
> > > + ASPEED ast2600 platform equipped with 16 I2C controllers each i2c controller
> > > + have 1 byte transfer buffer(byte mode), 32 bytes buffer(buffer mode), and
> > > + share a DMA engine.
> > > + Select I2C transfer mode for this controller. Supported values are:
> > > + - "byte": Use 1 byte for i2c transmit (1-byte buffer).
> > > + - "buffer": Use buffer (32-byte buffer) for i2c transmit. (default)
> > > + Better performance then byte mode.
> >
> > Good, I like worse performance so I can use byte mode.
> Thanks your review.
> Will remove performance statement.
I don't think that really addresses Rob's point there.
The selection of mode is somewhat a driver implementation decision (and
so would not belong in a DT binding) - *except* that there are
considerations around the use of hardware DMA channels, as covered in
earlier review.
[My understanding is that the mode needs to be defined here to select
which i2c devices have a DMA channel allocated to them. I also
think that byte mode may be useful in some scenarios, but that
consideration certainly does not belong in the DT binding spec]
So, how about we refine this to *just* the hardware-specific component:
whether a DMA channel is allocated. A driver implementation can then
select the appropriate mode (dma, byte or buffer), depending on
implementation-specific details.
In that case, we would just have a boolean property, like:
aspeed,i2c-dma-enabled;
- to signify that this controller may use a DMA channel. The choice of
actual mode is left up to the driver implementation.
Rob, would that suit better?
This way, we don't have ambiguity on "buffer" default vs. absent
property, and we're no longer specifying actual driver behaviour in the
DT.
Cheers,
Jeremy
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-16 1:49 ` Jeremy Kerr
@ 2026-03-16 16:47 ` Rob Herring
2026-03-17 0:52 ` Jeremy Kerr
0 siblings, 1 reply; 18+ messages in thread
From: Rob Herring @ 2026-03-16 16:47 UTC (permalink / raw)
To: Jeremy Kerr
Cc: Ryan Chen, andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
On Sun, Mar 15, 2026 at 8:50 PM Jeremy Kerr <jk@codeconstruct.com.au> wrote:
>
> Hi Ryan & Rob,
>
> > > > + aspeed,transfer-mode:
> > > > + description: |
> > > > + ASPEED ast2600 platform equipped with 16 I2C controllers each i2c controller
> > > > + have 1 byte transfer buffer(byte mode), 32 bytes buffer(buffer mode), and
> > > > + share a DMA engine.
> > > > + Select I2C transfer mode for this controller. Supported values are:
> > > > + - "byte": Use 1 byte for i2c transmit (1-byte buffer).
> > > > + - "buffer": Use buffer (32-byte buffer) for i2c transmit. (default)
> > > > + Better performance then byte mode.
> > >
> > > Good, I like worse performance so I can use byte mode.
> > Thanks your review.
> > Will remove performance statement.
>
> I don't think that really addresses Rob's point there.
>
> The selection of mode is somewhat a driver implementation decision (and
> so would not belong in a DT binding) - *except* that there are
> considerations around the use of hardware DMA channels, as covered in
> earlier review.
Am I supposed to go read the prior 25 versions?
> [My understanding is that the mode needs to be defined here to select
> which i2c devices have a DMA channel allocated to them. I also
> think that byte mode may be useful in some scenarios, but that
> consideration certainly does not belong in the DT binding spec]
But this is selecting DMA for the bus, not specific devices. I would
think the decision would be dynamic based on some xfer size. Certainly
if the xfer is less than the buffer size (32bytes), then there is no
advantage of DMA.
Or do you mean some instances of the I2C controllers have DMA and some
do not? If so, then ...
> So, how about we refine this to *just* the hardware-specific component:
> whether a DMA channel is allocated. A driver implementation can then
> select the appropriate mode (dma, byte or buffer), depending on
> implementation-specific details.
>
> In that case, we would just have a boolean property, like:
>
> aspeed,i2c-dma-enabled;
... yes, this is fine.
>
> - to signify that this controller may use a DMA channel. The choice of
> actual mode is left up to the driver implementation.
>
> Rob, would that suit better?
>
> This way, we don't have ambiguity on "buffer" default vs. absent
> property, and we're no longer specifying actual driver behaviour in the
> DT.
>
> Cheers,
>
>
> Jeremy
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-16 16:47 ` Rob Herring
@ 2026-03-17 0:52 ` Jeremy Kerr
2026-03-17 1:36 ` Ryan Chen
0 siblings, 1 reply; 18+ messages in thread
From: Jeremy Kerr @ 2026-03-17 0:52 UTC (permalink / raw)
To: Rob Herring
Cc: Ryan Chen, andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
Hi Rob,
> > I don't think that really addresses Rob's point there.
> >
> > The selection of mode is somewhat a driver implementation decision (and
> > so would not belong in a DT binding) - *except* that there are
> > considerations around the use of hardware DMA channels, as covered in
> > earlier review.
>
> Am I supposed to go read the prior 25 versions?
Not at all - the next paragraph was my attempt at a recap of those, but
Ryan, please correct me if I am wrong on any of those points.
> > [My understanding is that the mode needs to be defined here to select
> > which i2c devices have a DMA channel allocated to them. I also
> > think that byte mode may be useful in some scenarios, but that
> > consideration certainly does not belong in the DT binding spec]
>
> But this is selecting DMA for the bus, not specific devices. I would
> think the decision would be dynamic based on some xfer size. Certainly
> if the xfer is less than the buffer size (32bytes), then there is no
> advantage of DMA.
>
> Or do you mean some instances of the I2C controllers have DMA and some
> do not?
Yes, some of the controllers may be allocated a DMA channel. A driver
implementation may (or may not) make use of that channel.
Since the hardware has a limited numbers of DMA channels, Ryan's aim
here is to specify which controllers may consume a channel.
(in relation to the 'bus' terminology though: there is a 1:1 mapping
between i2c buses and controllers here, plus a small area of global
registers which apply to all controller peripherals)
> If so, then ...
[...]
> > In that case, we would just have a boolean property, like:
> >
> > aspeed,i2c-dma-enabled;
>
> ... yes, this is fine.
Brilliant, thanks.
Ryan: I think this gives us a much cleaner approach to the binding.
Cheers,
Jeremy
^ permalink raw reply [flat|nested] 18+ messages in thread
* RE: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-17 0:52 ` Jeremy Kerr
@ 2026-03-17 1:36 ` Ryan Chen
2026-03-17 1:43 ` Jeremy Kerr
2026-03-18 1:55 ` Jeremy Kerr
0 siblings, 2 replies; 18+ messages in thread
From: Ryan Chen @ 2026-03-17 1:36 UTC (permalink / raw)
To: Jeremy Kerr, Rob Herring
Cc: andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
> Subject: Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs
> and transfer-mode properties
>
> Hi Rob,
>
> > > I don't think that really addresses Rob's point there.
> > >
> > > The selection of mode is somewhat a driver implementation decision
> > > (and so would not belong in a DT binding) - *except* that there are
> > > considerations around the use of hardware DMA channels, as covered
> > > in earlier review.
> >
> > Am I supposed to go read the prior 25 versions?
>
> Not at all - the next paragraph was my attempt at a recap of those, but Ryan,
> please correct me if I am wrong on any of those points.
Your understanding is correct; the byte and buffer mode is mostly the same.
And also mode should be decided before xfer, due to the controller/target
both use the same xfer mode, not decide by transfer time.
The original my submit is only buffer mode and dma mode, and use only one
Boolean property, aspeed,i2c-dma-enabled, but someone suggest add byte
mode select, so I start to add at v17. I can drop the byte mode, if this is confused.
byte mode request:
https://lore.kernel.org/all/010e55e9-d58b-444c-ab57-ddf8c75f2390@gmail.com/
>
> > > [My understanding is that the mode needs to be defined here to
> > > select which i2c devices have a DMA channel allocated to them. I
> > > also think that byte mode may be useful in some scenarios, but that
> > > consideration certainly does not belong in the DT binding spec]
> >
> > But this is selecting DMA for the bus, not specific devices. I would
> > think the decision would be dynamic based on some xfer size. Certainly
> > if the xfer is less than the buffer size (32bytes), then there is no
> > advantage of DMA.
> >
> > Or do you mean some instances of the I2C controllers have DMA and some
> > do not?
>
> Yes, some of the controllers may be allocated a DMA channel. A driver
> implementation may (or may not) make use of that channel.
>
> Since the hardware has a limited numbers of DMA channels, Ryan's aim here is
> to specify which controllers may consume a channel.
Yes, in AST2600 DMA is shared, so it only can enable 1 channel dma, others use
buffer mode, and in next generation AST2700, all i2c channel can use dma.
>
> (in relation to the 'bus' terminology though: there is a 1:1 mapping between
> i2c buses and controllers here, plus a small area of global registers which apply
> to all controller peripherals)
>
> > If so, then ...
>
> [...]
>
> > > In that case, we would just have a boolean property, like:
> > >
> > > aspeed,i2c-dma-enabled;
> >
> > ... yes, this is fine.
>
> Brilliant, thanks.
>
> Ryan: I think this gives us a much cleaner approach to the binding.
Thanks the feedback, do you mean, just one boolean property for mode selection,
Am I right?
>
> Cheers,
>
>
> Jeremy
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-17 1:36 ` Ryan Chen
@ 2026-03-17 1:43 ` Jeremy Kerr
2026-03-17 1:48 ` Ryan Chen
2026-03-18 1:55 ` Jeremy Kerr
1 sibling, 1 reply; 18+ messages in thread
From: Jeremy Kerr @ 2026-03-17 1:43 UTC (permalink / raw)
To: Ryan Chen, Rob Herring
Cc: andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
Hi Ryan,
> Your understanding is correct; the byte and buffer mode is mostly the
> same. And also mode should be decided before xfer, due to the
> controller/target both use the same xfer mode, not decide by transfer
> time. The original my submit is only buffer mode and dma mode, and use
> only one Boolean property, aspeed,i2c-dma-enabled, but someone suggest
> add byte mode select, so I start to add at v17. I can drop the byte
> mode, if this is confused.
>
> byte mode request:
> https://lore.kernel.org/all/010e55e9-d58b-444c-ab57-
> ddf8c75f2390@gmail.com/
OK, that sounds like more driver configuration than hardware description
though.
> > Ryan: I think this gives us a much cleaner approach to the binding.
> Thanks the feedback, do you mean, just one boolean property for mode
> selection,
> Am I right?
It's less about "mode selection" (which is a driver implementation
consideration) and more about "hardware capability", which I think the
boolean property better represents.
The driver implementation could do whatever it likes with the
information about whether a DMA channel is allocated (and select a
suitable mode depending on that, and/or other runtime data).
This property only seems to be applicable to 2600 though, as there is no
need for it on 2700, if all controllers are DMA-capable.
Cheers,
Jeremy
^ permalink raw reply [flat|nested] 18+ messages in thread
* RE: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-17 1:43 ` Jeremy Kerr
@ 2026-03-17 1:48 ` Ryan Chen
0 siblings, 0 replies; 18+ messages in thread
From: Ryan Chen @ 2026-03-17 1:48 UTC (permalink / raw)
To: Jeremy Kerr, Rob Herring
Cc: andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
> Subject: Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs
> and transfer-mode properties
>
> Hi Ryan,
>
> > Your understanding is correct; the byte and buffer mode is mostly the
> > same. And also mode should be decided before xfer, due to the
> > controller/target both use the same xfer mode, not decide by transfer
> > time. The original my submit is only buffer mode and dma mode, and use
> > only one Boolean property, aspeed,i2c-dma-enabled, but someone suggest
> > add byte mode select, so I start to add at v17. I can drop the byte
> > mode, if this is confused.
> >
> > byte mode request:
> > https://lore.kernel.org/all/010e55e9-d58b-444c-ab57-
> > ddf8c75f2390@gmail.com/
>
> OK, that sounds like more driver configuration than hardware description
> though.
>
> > > Ryan: I think this gives us a much cleaner approach to the binding.
> > Thanks the feedback, do you mean, just one boolean property for mode
> > selection, Am I right?
>
> It's less about "mode selection" (which is a driver implementation
> consideration) and more about "hardware capability", which I think the
> boolean property better represents.
>
> The driver implementation could do whatever it likes with the information
> about whether a DMA channel is allocated (and select a suitable mode
> depending on that, and/or other runtime data).
>
> This property only seems to be applicable to 2600 though, as there is no need
> for it on 2700, if all controllers are DMA-capable.
>
Thanks the input, I will modify support boolean property aspeed,i2c-dma-enabled,
Yes, ast2700 all controller support DMA.
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-17 1:36 ` Ryan Chen
2026-03-17 1:43 ` Jeremy Kerr
@ 2026-03-18 1:55 ` Jeremy Kerr
2026-03-18 2:38 ` Ryan Chen
1 sibling, 1 reply; 18+ messages in thread
From: Jeremy Kerr @ 2026-03-18 1:55 UTC (permalink / raw)
To: Ryan Chen, Rob Herring
Cc: andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
Hi Ryan,
> > Not at all - the next paragraph was my attempt at a recap of those, but Ryan,
> > please correct me if I am wrong on any of those points.
>
> Your understanding is correct; the byte and buffer mode is mostly the same.
> And also mode should be decided before xfer, due to the controller/target
> both use the same xfer mode, not decide by transfer time.
> The original my submit is only buffer mode and dma mode, and use only one
> Boolean property, aspeed,i2c-dma-enabled, but someone suggest add byte
> mode select, so I start to add at v17. I can drop the byte mode, if this is confused.
>
> byte mode request:
> https://lore.kernel.org/all/010e55e9-d58b-444c-ab57-ddf8c75f2390@gmail.com/
I understand that there may be valid uses for byte mode, but that does
not mean the configuration belongs in the device tree.
We do not seem to have much data on what those valid uses are, but I am
assuming it is not an attribute of the controller peripheral hardware.
[As an example: I suspect MCTP cannot be fully spec-compliant without
byte mode, in order to support the NAK window on target-mode RX. In that
case we can enforce byte mode when the controller is selected for MCTP
use, without requiring a mode selection property in the DT]
> > Ryan: I think this gives us a much cleaner approach to the binding.
> Thanks the feedback, do you mean, just one boolean property for mode selection,
> Am I right?
The property would not select a mode, it just indicates whether DMA is
available.
A driver implementation can use that indication, along with any other
configuration data, in order to select a mode. The Linux driver
implementation may use other runtime facilities to control that
selection, if you need, like sysfs or configfs.
Cheers,
Jeremy
^ permalink raw reply [flat|nested] 18+ messages in thread
* RE: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-18 1:55 ` Jeremy Kerr
@ 2026-03-18 2:38 ` Ryan Chen
2026-03-18 3:55 ` Jeremy Kerr
0 siblings, 1 reply; 18+ messages in thread
From: Ryan Chen @ 2026-03-18 2:38 UTC (permalink / raw)
To: Jeremy Kerr, Rob Herring
Cc: andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
> Subject: Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs
> and transfer-mode properties
>
> Hi Ryan,
>
> > > Not at all - the next paragraph was my attempt at a recap of those,
> > > but Ryan, please correct me if I am wrong on any of those points.
> >
> > Your understanding is correct; the byte and buffer mode is mostly the same.
> > And also mode should be decided before xfer, due to the
> > controller/target both use the same xfer mode, not decide by transfer time.
> > The original my submit is only buffer mode and dma mode, and use only
> > one Boolean property, aspeed,i2c-dma-enabled, but someone suggest add
> > byte mode select, so I start to add at v17. I can drop the byte mode, if this is
> confused.
> >
> > byte mode request:
> > https://lore.kernel.org/all/010e55e9-d58b-444c-ab57-ddf8c75f2390@gmail
> > .com/
>
> I understand that there may be valid uses for byte mode, but that does not
> mean the configuration belongs in the device tree.
>
> We do not seem to have much data on what those valid uses are, but I am
> assuming it is not an attribute of the controller peripheral hardware.
OK will remove it in yaml file, instead Boolean property, aspeed,i2c-dma-enabled
>
> [As an example: I suspect MCTP cannot be fully spec-compliant without byte
> mode, in order to support the NAK window on target-mode RX. In that case we
> can enforce byte mode when the controller is selected for MCTP use, without
> requiring a mode selection property in the DT]
>
> > > Ryan: I think this gives us a much cleaner approach to the binding.
> > Thanks the feedback, do you mean, just one boolean property for mode
> > selection, Am I right?
>
> The property would not select a mode, it just indicates whether DMA is
> available.
>
> A driver implementation can use that indication, along with any other
> configuration data, in order to select a mode. The Linux driver implementation
> may use other runtime facilities to control that selection, if you need, like sysfs
> or configfs.
Do you mean sysfs select support mode selection(byte, buffer, dma)
Or just force byte mode?
>
> Cheers,
>
>
> Jeremy
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-18 2:38 ` Ryan Chen
@ 2026-03-18 3:55 ` Jeremy Kerr
2026-03-18 3:59 ` Jeremy Kerr
0 siblings, 1 reply; 18+ messages in thread
From: Jeremy Kerr @ 2026-03-18 3:55 UTC (permalink / raw)
To: Ryan Chen, Rob Herring
Cc: andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
Hi Ryan,
> Do you mean sysfs select support mode selection(byte, buffer, dma)
> Or just force byte mode?
I would think that the best approach would be a mechanism to specify the
mode - either byte, buffer, or DMA - if DMA is indicated as available to
the controller.
Cheers,
Jeremy
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-18 3:55 ` Jeremy Kerr
@ 2026-03-18 3:59 ` Jeremy Kerr
2026-03-18 6:14 ` Ryan Chen
0 siblings, 1 reply; 18+ messages in thread
From: Jeremy Kerr @ 2026-03-18 3:59 UTC (permalink / raw)
To: Ryan Chen, Rob Herring
Cc: andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
Hi Ryan,
> > Do you mean sysfs select support mode selection(byte, buffer, dma)
> > Or just force byte mode?
>
> I would think that the best approach would be a mechanism to specify the
> mode - either byte, buffer, or DMA - if DMA is indicated as available to
> the controller.
... with a sensible default mode (DMA if it is available, buffer if
not).
But none of that logic relates to the binding, it's all driver
implementation detail.
Cheers,
Jeremy
^ permalink raw reply [flat|nested] 18+ messages in thread
* RE: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties
2026-03-18 3:59 ` Jeremy Kerr
@ 2026-03-18 6:14 ` Ryan Chen
0 siblings, 0 replies; 18+ messages in thread
From: Ryan Chen @ 2026-03-18 6:14 UTC (permalink / raw)
To: Jeremy Kerr, Rob Herring
Cc: andriy.shevchenko@linux.intel.com, Andi Shyti,
Krzysztof Kozlowski, Conor Dooley, Joel Stanley, Andrew Jeffery,
Benjamin Herrenschmidt, Philipp Zabel, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
openbmc@lists.ozlabs.org
> Subject: Re: [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs
> and transfer-mode properties
>
> Hi Ryan,
>
> > > Do you mean sysfs select support mode selection(byte, buffer, dma)
> > > Or just force byte mode?
> >
> > I would think that the best approach would be a mechanism to specify
> > the mode - either byte, buffer, or DMA - if DMA is indicated as
> > available to the controller.
>
> ... with a sensible default mode (DMA if it is available, buffer if not).
>
> But none of that logic relates to the binding, it's all driver implementation
> detail.
I will add new dma_available in struct ast2600_i2c_bus, align with dma property.
i2c_bus->dma_available = device_property_read_bool(dev, "aspeed,enable-dma");
And add sysfs for xfer_mode
static ssize_t xfer_mode_show(struct device *dev, struct device_attribute *attr, char *buf)
static ssize_t xfer_mode_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
^ permalink raw reply [flat|nested] 18+ messages in thread
end of thread, other threads:[~2026-03-18 6:15 UTC | newest]
Thread overview: 18+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-03-09 6:53 [PATCH v26 0/4] Add ASPEED AST2600 I2C controller driver Ryan Chen
2026-03-09 6:53 ` [PATCH v26 1/4] dt-bindings: i2c: Split AST2600 binding into a new YAML Ryan Chen
2026-03-09 6:53 ` [PATCH v26 2/4] dt-bindings: i2c: ast2600-i2c.yaml: Add global-regs and transfer-mode properties Ryan Chen
2026-03-13 23:21 ` Rob Herring
2026-03-14 0:24 ` Ryan Chen
2026-03-16 1:49 ` Jeremy Kerr
2026-03-16 16:47 ` Rob Herring
2026-03-17 0:52 ` Jeremy Kerr
2026-03-17 1:36 ` Ryan Chen
2026-03-17 1:43 ` Jeremy Kerr
2026-03-17 1:48 ` Ryan Chen
2026-03-18 1:55 ` Jeremy Kerr
2026-03-18 2:38 ` Ryan Chen
2026-03-18 3:55 ` Jeremy Kerr
2026-03-18 3:59 ` Jeremy Kerr
2026-03-18 6:14 ` Ryan Chen
2026-03-09 6:53 ` [PATCH v26 3/4] i2c: ast2600: Add controller driver for AST2600 new register set Ryan Chen
2026-03-09 6:53 ` [PATCH v26 4/4] i2c: ast2600: Add target mode support Ryan Chen
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