[PATCH 0/2] soc: ti: wkup_m3_ipc: Add support for IO Isolation

[PATCH 0/2] soc: ti: wkup_m3_ipc: Add support for IO Isolation

[Drew Fustini]

TI AM437x SoCs support isolation of the IOs so that control is taken
from the peripheral they are connected to and overridden by values
present in the control register for that pad. This series documents a
new property 'ti,io-isolation' and updates the wkup_m3_ipc driver to 
inform the CM3 firmware when that property is set.

A prerequisite for this series is: 
[PATCH v2 0/2] soc: ti: wkup_m3_ipc: support vtt toggle
https://lore.kernel.org/lkml/20220409211215.2529387-1-dfustini@baylibre.com/T/

Dave Gerlach (1):
  soc: ti: wkup_m3_ipc: Add support for IO Isolation

Drew Fustini (1):
  dt-bindings: wkup-m3-ipc: Add ti,io-isolation property

 .../bindings/soc/ti/wkup-m3-ipc.yaml          | 68 +++++++++++++++++--
 drivers/soc/ti/wkup_m3_ipc.c                  | 14 +++-
 include/linux/wkup_m3_ipc.h                   |  1 +
 3 files changed, 76 insertions(+), 7 deletions(-)

-- 
2.32.0

[PATCH 1/2] dt-bindings: wkup-m3-ipc: Add ti,io-isolation property

[Drew Fustini]

Add documentation for the ti,io-isolation DT property on the wkup_m3_ipc
node which tells the wkup_m3_ipc driver to use the wkup_m3 to enable
IO Isolation during low power mode transitions on am43xx platforms.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
[dfustini: convert to YAML, make DTS example that passes check]
Signed-off-by: Drew Fustini <dfustini@baylibre.com>
---
 .../bindings/soc/ti/wkup-m3-ipc.yaml          | 68 +++++++++++++++++--
 1 file changed, 63 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
index 7f4a75c5fcaa..30a65b75c024 100644
--- a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
+++ b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
@@ -24,14 +24,22 @@ description: |+
   A wkup_m3_ipc device node is used to represent the IPC registers within an
   SoC.
 
-  Support for VTT Toggle
-  ==================================
+  Support for VTT Toggle with GPIO pin
+  ====================================
   On some boards like the AM335x EVM-SK and the AM437x GP EVM, a GPIO pin is
   connected to the enable pin on the DDR VTT regulator. This allows the
   regulator to be disabled upon suspend and enabled upon resume. Please note
   that the GPIO pin must be part of the GPIO0 module as only this GPIO module
   is in the wakeup power domain.
 
+  Support for IO Isolation
+  ========================
+  On AM437x SoCs, certain pins can be forced into an alternate state when IO
+  isolation is activated. Those pins have pad control registers prefixed by
+  'CTRL_CONF_' that contain DS0 (e.g. deep sleep) configuration bits that can
+  override the pin's existing bias (pull-up/pull-down) and value (high/low) when
+  IO isolation is active.
+
 properties:
   compatible:
     enum:
@@ -63,6 +71,14 @@ properties:
     $ref: /schemas/types.yaml#/definitions/uint32
     description: GPIO pin connected to enable pin on VTT regulator
 
+  ti,set-io-isolation:
+    type: boolean
+    description:
+      If this property is present, then the wkup_m3_ipc driver will instruct
+      the CM3 firmware to activate IO isolation when suspending to deep sleep.
+      This can be leveraged by a board design to put other devices on the board
+      into a low power state.
+
 required:
   - compatible
   - reg
@@ -74,21 +90,63 @@ additionalProperties: false
 
 examples:
   - |
+    /* Example for AM335x SoC */
     soc {
         #address-cells = <1>;
         #size-cells = <1>;
 
-        mailbox: mailbox {
+        am335x_mailbox: mailbox {
             #mbox-cells = <1>;
         };
 
-        wkup_m3_ipc: wkup_m3_ipc@1324 {
+        wkup_m3_ipc@1324 {
            compatible = "ti,am3352-wkup-m3-ipc";
            reg = <0x1324 0x24>;
            interrupts = <78>;
            ti,rproc = <&wkup_m3>;
-           mboxes = <&mailbox &mbox_wkupm3>;
+           mboxes = <&am335x_mailbox &mbox_wkupm3>;
            ti,vtt-gpio-pin = <7>;
         };
     };
+
+  - |
+    /*
+     * Example for AM473x SoC:
+     * On the AM437x-GP-EVM board, gpio5_7 is wired to enable pin of the DDR VTT
+     * regulator. The 'ddr_vtt_toggle_default' pinmux node configures gpio5_7
+     * for pull-up during normal system operation. However, the DS0 (deep sleep)
+     * state of the pin is configured for pull-down and thus the VTT regulator
+     * will be disabled to save power when IO isolation is active. Note that
+     * this method is an alternative to using the 'ti,vtt-gpio-pin' property.
+     */
+    #include <dt-bindings/pinctrl/am43xx.h>
+    soc {
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        am437x_mailbox: mailbox {
+            #mbox-cells = <1>;
+        };
+
+        am43xx_pinmux {
+            pinctrl-names = "default";
+            pinctrl-0 = <&ddr3_vtt_toggle_default>;
+
+            ddr3_vtt_toggle_default: ddr_vtt_toggle_default {
+                 pinctrl-single,pins = <
+                    0x25C (DS0_PULL_UP_DOWN_EN | PIN_OUTPUT_PULLUP | DS0_FORCE_OFF_MODE | MUX_MODE7)
+                 >;
+            };
+        };
+
+        wkup_m3_ipc@1324 {
+           compatible = "ti,am4372-wkup-m3-ipc";
+           reg = <0x1324 0x24>;
+           interrupts = <78>;
+           ti,rproc = <&wkup_m3>;
+           mboxes = <&am437x_mailbox &mbox_wkupm3>;
+           ti,set-io-isolation;
+        };
+    };
+
 ...
-- 
2.32.0

Re: [PATCH 1/2] dt-bindings: wkup-m3-ipc: Add ti,io-isolation property

[Rob Herring]

On Tue, Apr 12, 2022 at 07:06:40PM -0700, Drew Fustini wrote:
> Add documentation for the ti,io-isolation DT property on the wkup_m3_ipc
> node which tells the wkup_m3_ipc driver to use the wkup_m3 to enable
> IO Isolation during low power mode transitions on am43xx platforms.
> 
> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
> [dfustini: convert to YAML, make DTS example that passes check]
> Signed-off-by: Drew Fustini <dfustini@baylibre.com>
> ---
>  .../bindings/soc/ti/wkup-m3-ipc.yaml          | 68 +++++++++++++++++--
>  1 file changed, 63 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
> index 7f4a75c5fcaa..30a65b75c024 100644
> --- a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
> +++ b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
> @@ -24,14 +24,22 @@ description: |+
>    A wkup_m3_ipc device node is used to represent the IPC registers within an
>    SoC.
>  
> -  Support for VTT Toggle
> -  ==================================
> +  Support for VTT Toggle with GPIO pin
> +  ====================================
>    On some boards like the AM335x EVM-SK and the AM437x GP EVM, a GPIO pin is
>    connected to the enable pin on the DDR VTT regulator. This allows the
>    regulator to be disabled upon suspend and enabled upon resume. Please note
>    that the GPIO pin must be part of the GPIO0 module as only this GPIO module
>    is in the wakeup power domain.
>  
> +  Support for IO Isolation
> +  ========================
> +  On AM437x SoCs, certain pins can be forced into an alternate state when IO
> +  isolation is activated. Those pins have pad control registers prefixed by
> +  'CTRL_CONF_' that contain DS0 (e.g. deep sleep) configuration bits that can
> +  override the pin's existing bias (pull-up/pull-down) and value (high/low) when
> +  IO isolation is active.

Can't this feature be implied from the compatible string?

> +
>  properties:
>    compatible:
>      enum:
> @@ -63,6 +71,14 @@ properties:
>      $ref: /schemas/types.yaml#/definitions/uint32
>      description: GPIO pin connected to enable pin on VTT regulator
>  
> +  ti,set-io-isolation:
> +    type: boolean
> +    description:
> +      If this property is present, then the wkup_m3_ipc driver will instruct
> +      the CM3 firmware to activate IO isolation when suspending to deep sleep.
> +      This can be leveraged by a board design to put other devices on the board
> +      into a low power state.
> +
>  required:
>    - compatible
>    - reg
> @@ -74,21 +90,63 @@ additionalProperties: false
>  
>  examples:
>    - |
> +    /* Example for AM335x SoC */
>      soc {
>          #address-cells = <1>;
>          #size-cells = <1>;
>  
> -        mailbox: mailbox {
> +        am335x_mailbox: mailbox {
>              #mbox-cells = <1>;
>          };
>  
> -        wkup_m3_ipc: wkup_m3_ipc@1324 {
> +        wkup_m3_ipc@1324 {
>             compatible = "ti,am3352-wkup-m3-ipc";
>             reg = <0x1324 0x24>;
>             interrupts = <78>;
>             ti,rproc = <&wkup_m3>;
> -           mboxes = <&mailbox &mbox_wkupm3>;
> +           mboxes = <&am335x_mailbox &mbox_wkupm3>;
>             ti,vtt-gpio-pin = <7>;
>          };
>      };
> +
> +  - |
> +    /*
> +     * Example for AM473x SoC:
> +     * On the AM437x-GP-EVM board, gpio5_7 is wired to enable pin of the DDR VTT
> +     * regulator. The 'ddr_vtt_toggle_default' pinmux node configures gpio5_7
> +     * for pull-up during normal system operation. However, the DS0 (deep sleep)
> +     * state of the pin is configured for pull-down and thus the VTT regulator
> +     * will be disabled to save power when IO isolation is active. Note that
> +     * this method is an alternative to using the 'ti,vtt-gpio-pin' property.
> +     */
> +    #include <dt-bindings/pinctrl/am43xx.h>
> +    soc {
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +
> +        am437x_mailbox: mailbox {
> +            #mbox-cells = <1>;
> +        };
> +
> +        am43xx_pinmux {
> +            pinctrl-names = "default";
> +            pinctrl-0 = <&ddr3_vtt_toggle_default>;
> +
> +            ddr3_vtt_toggle_default: ddr_vtt_toggle_default {
> +                 pinctrl-single,pins = <
> +                    0x25C (DS0_PULL_UP_DOWN_EN | PIN_OUTPUT_PULLUP | DS0_FORCE_OFF_MODE | MUX_MODE7)
> +                 >;
> +            };
> +        };
> +
> +        wkup_m3_ipc@1324 {
> +           compatible = "ti,am4372-wkup-m3-ipc";
> +           reg = <0x1324 0x24>;
> +           interrupts = <78>;
> +           ti,rproc = <&wkup_m3>;
> +           mboxes = <&am437x_mailbox &mbox_wkupm3>;
> +           ti,set-io-isolation;
> +        };
> +    };
> +
>  ...
> -- 
> 2.32.0
> 
> 

Re: [PATCH 1/2] dt-bindings: wkup-m3-ipc: Add ti,io-isolation property

[Dave Gerlach]

Hi,

On 4/14/22 07:34, Rob Herring wrote:
> On Tue, Apr 12, 2022 at 07:06:40PM -0700, Drew Fustini wrote:
>> Add documentation for the ti,io-isolation DT property on the wkup_m3_ipc
>> node which tells the wkup_m3_ipc driver to use the wkup_m3 to enable
>> IO Isolation during low power mode transitions on am43xx platforms.
>>

$subject should be 'ti,set-io-isolation'.

>> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
>> [dfustini: convert to YAML, make DTS example that passes check]
>> Signed-off-by: Drew Fustini <dfustini@baylibre.com>
>> ---
>>  .../bindings/soc/ti/wkup-m3-ipc.yaml          | 68 +++++++++++++++++--
>>  1 file changed, 63 insertions(+), 5 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
>> index 7f4a75c5fcaa..30a65b75c024 100644
>> --- a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
>> +++ b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
>> @@ -24,14 +24,22 @@ description: |+
>>    A wkup_m3_ipc device node is used to represent the IPC registers within an
>>    SoC.
>>  
>> -  Support for VTT Toggle
>> -  ==================================
>> +  Support for VTT Toggle with GPIO pin
>> +  ====================================
>>    On some boards like the AM335x EVM-SK and the AM437x GP EVM, a GPIO pin is
>>    connected to the enable pin on the DDR VTT regulator. This allows the
>>    regulator to be disabled upon suspend and enabled upon resume. Please note
>>    that the GPIO pin must be part of the GPIO0 module as only this GPIO module
>>    is in the wakeup power domain.
>>  
>> +  Support for IO Isolation
>> +  ========================
>> +  On AM437x SoCs, certain pins can be forced into an alternate state when IO
>> +  isolation is activated. Those pins have pad control registers prefixed by
>> +  'CTRL_CONF_' that contain DS0 (e.g. deep sleep) configuration bits that can
>> +  override the pin's existing bias (pull-up/pull-down) and value (high/low) when
>> +  IO isolation is active.
> 
> Can't this feature be implied from the compatible string?

All AM437x SoCs support it, but it may be enabled/disabled on different
boards. For example, this will be set for am437x-gp-evm, but not
am43x-epos-evm.

Regards,
Dave

> 
>> +
>>  properties:
>>    compatible:
>>      enum:
>> @@ -63,6 +71,14 @@ properties:
>>      $ref: /schemas/types.yaml#/definitions/uint32
>>      description: GPIO pin connected to enable pin on VTT regulator
>>  
>> +  ti,set-io-isolation:
>> +    type: boolean
>> +    description:
>> +      If this property is present, then the wkup_m3_ipc driver will instruct
>> +      the CM3 firmware to activate IO isolation when suspending to deep sleep.
>> +      This can be leveraged by a board design to put other devices on the board
>> +      into a low power state.
>> +
>>  required:
>>    - compatible
>>    - reg
>> @@ -74,21 +90,63 @@ additionalProperties: false
>>  
>>  examples:
>>    - |
>> +    /* Example for AM335x SoC */
>>      soc {
>>          #address-cells = <1>;
>>          #size-cells = <1>;
>>  
>> -        mailbox: mailbox {
>> +        am335x_mailbox: mailbox {
>>              #mbox-cells = <1>;
>>          };
>>  
>> -        wkup_m3_ipc: wkup_m3_ipc@1324 {
>> +        wkup_m3_ipc@1324 {
>>             compatible = "ti,am3352-wkup-m3-ipc";
>>             reg = <0x1324 0x24>;
>>             interrupts = <78>;
>>             ti,rproc = <&wkup_m3>;
>> -           mboxes = <&mailbox &mbox_wkupm3>;
>> +           mboxes = <&am335x_mailbox &mbox_wkupm3>;
>>             ti,vtt-gpio-pin = <7>;
>>          };
>>      };
>> +
>> +  - |
>> +    /*
>> +     * Example for AM473x SoC:
>> +     * On the AM437x-GP-EVM board, gpio5_7 is wired to enable pin of the DDR VTT
>> +     * regulator. The 'ddr_vtt_toggle_default' pinmux node configures gpio5_7
>> +     * for pull-up during normal system operation. However, the DS0 (deep sleep)
>> +     * state of the pin is configured for pull-down and thus the VTT regulator
>> +     * will be disabled to save power when IO isolation is active. Note that
>> +     * this method is an alternative to using the 'ti,vtt-gpio-pin' property.
>> +     */
>> +    #include <dt-bindings/pinctrl/am43xx.h>
>> +    soc {
>> +        #address-cells = <1>;
>> +        #size-cells = <1>;
>> +
>> +        am437x_mailbox: mailbox {
>> +            #mbox-cells = <1>;
>> +        };
>> +
>> +        am43xx_pinmux {
>> +            pinctrl-names = "default";
>> +            pinctrl-0 = <&ddr3_vtt_toggle_default>;
>> +
>> +            ddr3_vtt_toggle_default: ddr_vtt_toggle_default {
>> +                 pinctrl-single,pins = <
>> +                    0x25C (DS0_PULL_UP_DOWN_EN | PIN_OUTPUT_PULLUP | DS0_FORCE_OFF_MODE | MUX_MODE7)
>> +                 >;
>> +            };
>> +        };
>> +
>> +        wkup_m3_ipc@1324 {
>> +           compatible = "ti,am4372-wkup-m3-ipc";
>> +           reg = <0x1324 0x24>;
>> +           interrupts = <78>;
>> +           ti,rproc = <&wkup_m3>;
>> +           mboxes = <&am437x_mailbox &mbox_wkupm3>;
>> +           ti,set-io-isolation;
>> +        };
>> +    };
>> +
>>  ...
>> -- 
>> 2.32.0
>>
>>

[PATCH 2/2] soc: ti: wkup_m3_ipc: Add support for IO Isolation

[Drew Fustini]

From: Dave Gerlach <d-gerlach@ti.com>

AM43xx support isolation of the IOs so that control is taken
from the peripheral they are connected to and overridden by values
present in the CTRL_CONF_* registers for the pad in the control module.

The actual toggling happens from the wkup_m3, so use a DT property from
the wkup_m3_ipc node to allow the PM code to communicate the necessity
for placing the IOs into isolation to the firmware.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Drew Fustini <dfustini@baylibre.com>
---
 drivers/soc/ti/wkup_m3_ipc.c | 14 ++++++++++++--
 include/linux/wkup_m3_ipc.h  |  1 +
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/ti/wkup_m3_ipc.c b/drivers/soc/ti/wkup_m3_ipc.c
index 247a4b57a372..988162dd153a 100644
--- a/drivers/soc/ti/wkup_m3_ipc.c
+++ b/drivers/soc/ti/wkup_m3_ipc.c
@@ -46,6 +46,8 @@
 #define IPC_VTT_STAT_MASK		(0x1 << 3)
 #define IPC_VTT_GPIO_PIN_SHIFT		(0x4)
 #define IPC_VTT_GPIO_PIN_MASK		(0x3f << 4)
+#define IPC_IO_ISOLATION_STAT_SHIFT	(10)
+#define IPC_IO_ISOLATION_STAT_MASK	(0x1 << 10)
 
 #define M3_STATE_UNKNOWN		0
 #define M3_STATE_RESET			1
@@ -228,6 +230,11 @@ static void wkup_m3_set_vtt_gpio(struct wkup_m3_ipc *m3_ipc, int gpio)
 			    (gpio << IPC_VTT_GPIO_PIN_SHIFT);
 }
 
+static void wkup_m3_set_io_isolation(struct wkup_m3_ipc *m3_ipc)
+{
+	m3_ipc->isolation_conf = (1 << IPC_IO_ISOLATION_STAT_SHIFT);
+}
+
 /* Public functions */
 /**
  * wkup_m3_set_mem_type - Pass wkup_m3 which type of memory is in use
@@ -308,8 +315,8 @@ static int wkup_m3_prepare_low_power(struct wkup_m3_ipc *m3_ipc, int state)
 	wkup_m3_ctrl_ipc_write(m3_ipc, m3_ipc->resume_addr, 0);
 	wkup_m3_ctrl_ipc_write(m3_ipc, m3_power_state, 1);
 	wkup_m3_ctrl_ipc_write(m3_ipc, m3_ipc->mem_type |
-			       m3_ipc->vtt_conf, 4);
-
+			       m3_ipc->vtt_conf |
+			       m3_ipc->isolation_conf, 4);
 	wkup_m3_ctrl_ipc_write(m3_ipc, DS_IPC_DEFAULT, 2);
 	wkup_m3_ctrl_ipc_write(m3_ipc, DS_IPC_DEFAULT, 3);
 	wkup_m3_ctrl_ipc_write(m3_ipc, DS_IPC_DEFAULT, 5);
@@ -518,6 +525,9 @@ static int wkup_m3_ipc_probe(struct platform_device *pdev)
 			dev_warn(dev, "Invalid VTT GPIO(%d) pin\n", temp);
 	}
 
+	if (of_find_property(np, "ti,set-io-isolation", NULL))
+		wkup_m3_set_io_isolation(m3_ipc);
+
 	/*
 	 * Wait for firmware loading completion in a thread so we
 	 * can boot the wkup_m3 as soon as it's ready without holding
diff --git a/include/linux/wkup_m3_ipc.h b/include/linux/wkup_m3_ipc.h
index 2bc52c6381d5..b706eac58f92 100644
--- a/include/linux/wkup_m3_ipc.h
+++ b/include/linux/wkup_m3_ipc.h
@@ -34,6 +34,7 @@ struct wkup_m3_ipc {
 	int mem_type;
 	unsigned long resume_addr;
 	int vtt_conf;
+	int isolation_conf;
 	int state;
 
 	struct completion sync_complete;
-- 
2.32.0