[PATCH v7 1/2] i2c: add support for microchip fpga i2c controllers

Conor Dooley
2022-07-06T14:13:40Z

Add Microchip CoreI2C i2c controller support. This driver supports the
"hard" i2c controller on the Microchip PolarFire SoC & the basic feature
set for "soft" i2c controller implemtations in the FPGA fabric.

Co-developed-by: Daire McNamara <daire.mcnamara@microchip.com>
Signed-off-by: Daire McNamara <daire.mcnamara@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
Changes from v6:
- dropped the unused spinlock
- switched the timeout to HZ
- renamed to i2c-microchip-corei2c
- fixed a useless < 0 check on a u16
- removed unused iopoll.h

Changes from v5:
- add zero to the invalid irq check

Changes from v4:
- reset the controller on xfer timeout
- sort the headers alphabetically

Changes from v3:
- update members in struct doc comment
- move mchp_corei2c_transfer in its caller
- change msg_len to a u16
- remove unused variable msg_read
- use adapater.timeout for completion
- dont use last_byte goto
- remove block on zero length messages
(the hardware can do them, was a carryover from the baremetal driver)
- probe:
- drop unneeded initialisation
- use ret not val
- explain shared irq
- disallow 0 bus_clock_rate
- include base in device name
- dropped the duplicate "microchip" in the registered print
(its in driver.name)

Changes from v2:
- Fixed whitespace in defines that I removed accidentally

Changes from v1:
- Use byte write and read functions
- Return IRQ_NONE and don't warn if not this drivers interrupt
- Add a clk_disable_unprepare to avoid leaking a clock in the probe
---
drivers/i2c/busses/Kconfig | 11 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-microchip-corei2c.c | 480 +++++++++++++++++++++
3 files changed, 492 insertions(+)
create mode 100644 drivers/i2c/busses/i2c-microchip-corei2c.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index b1d7069dd377..ccd6537cfd18 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -781,6 +781,17 @@ config I2C_MESON
If you say yes to this option, support will be included for the
I2C interface on the Amlogic Meson family of SoCs.

+config I2C_MICROCHIP_CORE
+ tristate "Microchip FPGA I2C controller"
+ depends on SOC_MICROCHIP_POLARFIRE || COMPILE_TEST
+ depends on OF
+ help
+ If you say yes to this option, support will be included for the
+ I2C interface on Microchip FPGAs.
+
+ This driver can also be built as a module. If so, the module will be
+ called i2c-microchip-core.
+
config I2C_MPC
tristate "MPC107/824x/85xx/512x/52xx/83xx/86xx"
depends on PPC
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index b0a10e5d9ee9..29d729b6a5b7 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -78,6 +78,7 @@ obj-$(CONFIG_I2C_JZ4780) += i2c-jz4780.o
obj-$(CONFIG_I2C_KEMPLD) += i2c-kempld.o
obj-$(CONFIG_I2C_LPC2K) += i2c-lpc2k.o
obj-$(CONFIG_I2C_MESON) += i2c-meson.o
+obj-$(CONFIG_I2C_MICROCHIP_CORE) += i2c-microchip-corei2c.o
obj-$(CONFIG_I2C_MPC) += i2c-mpc.o
obj-$(CONFIG_I2C_MT65XX) += i2c-mt65xx.o
obj-$(CONFIG_I2C_MT7621) += i2c-mt7621.o
diff --git a/drivers/i2c/busses/i2c-microchip-corei2c.c b/drivers/i2c/busses/i2c-microchip-corei2c.c
new file mode 100644
index 000000000000..6df0f1c33278
--- /dev/null
+++ b/drivers/i2c/busses/i2c-microchip-corei2c.c
@@ -0,0 +1,480 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip CoreI2C I2C controller driver
+ *
+ * Copyright (c) 2018-2022 Microchip Corporation. All rights reserved.
+ *
+ * Author: Daire McNamara <daire.mcnamara@microchip.com>
+ * Author: Conor Dooley <conor.dooley@microchip.com>
+ */
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define CORE_I2C_CTRL (0x00)
+#define CTRL_CR0 BIT(0)
+#define CTRL_CR1 BIT(1)
+#define CTRL_AA BIT(2)
+#define CTRL_SI BIT(3)
+#define CTRL_STO BIT(4)
+#define CTRL_STA BIT(5)
+#define CTRL_ENS1 BIT(6)
+#define CTRL_CR2 BIT(7)
+
+#define STATUS_BUS_ERROR (0x00)
+#define STATUS_M_START_SENT (0x08)
+#define STATUS_M_REPEATED_START_SENT (0x10)
+#define STATUS_M_SLAW_ACK (0x18)
+#define STATUS_M_SLAW_NACK (0x20)
+#define STATUS_M_TX_DATA_ACK (0x28)
+#define STATUS_M_TX_DATA_NACK (0x30)
+#define STATUS_M_ARB_LOST (0x38)
+#define STATUS_M_SLAR_ACK (0x40)
+#define STATUS_M_SLAR_NACK (0x48)
+#define STATUS_M_RX_DATA_ACKED (0x50)
+#define STATUS_M_RX_DATA_NACKED (0x58)
+#define STATUS_S_SLAW_ACKED (0x60)
+#define STATUS_S_ARB_LOST_SLAW_ACKED (0x68)
+#define STATUS_S_GENERAL_CALL_ACKED (0x70)
+#define STATUS_S_ARB_LOST_GENERAL_CALL_ACKED (0x78)
+#define STATUS_S_RX_DATA_ACKED (0x80)
+#define STATUS_S_RX_DATA_NACKED (0x88)
+#define STATUS_S_GENERAL_CALL_RX_DATA_ACKED (0x90)
+#define STATUS_S_GENERAL_CALL_RX_DATA_NACKED (0x98)
+#define STATUS_S_RX_STOP (0xA0)
+#define STATUS_S_SLAR_ACKED (0xA8)
+#define STATUS_S_ARB_LOST_SLAR_ACKED (0xB0)
+#define STATUS_S_TX_DATA_ACK (0xB8)
+#define STATUS_S_TX_DATA_NACK (0xC0)
+#define STATUS_LAST_DATA_ACK (0xC8)
+#define STATUS_M_SMB_MASTER_RESET (0xD0)
+#define STATUS_S_SCL_LOW_TIMEOUT (0xD8) /* 25 ms */
+#define STATUS_NO_STATE_INFO (0xF8)
+
+#define CORE_I2C_STATUS (0x04)
+#define CORE_I2C_DATA (0x08)
+#define WRITE_BIT (0x0)
+#define READ_BIT (0x1)
+#define SLAVE_ADDR_SHIFT (1)
+#define CORE_I2C_SLAVE0_ADDR (0x0c)
+#define GENERAL_CALL_BIT (0x0)
+#define CORE_I2C_SMBUS (0x10)
+#define SMBALERT_INT_ENB (0x0)
+#define SMBSUS_INT_ENB (0x1)
+#define SMBUS_ENB (0x2)
+#define SMBALERT_NI_STATUS (0x3)
+#define SMBALERT_NO_CTRL (0x4)
+#define SMBSUS_NI_STATUS (0x5)
+#define SMBSUS_NO_CTRL (0x6)
+#define SMBUS_RESET (0x7)
+#define CORE_I2C_FREQ (0x14)
+#define CORE_I2C_GLITCHREG (0x18)
+#define CORE_I2C_SLAVE1_ADDR (0x1c)
+
+#define PCLK_DIV_960 (CTRL_CR2)
+#define PCLK_DIV_256 (0)
+#define PCLK_DIV_224 (CTRL_CR0)
+#define PCLK_DIV_192 (CTRL_CR1)
+#define PCLK_DIV_160 (CTRL_CR0 | CTRL_CR1)
+#define PCLK_DIV_120 (CTRL_CR0 | CTRL_CR2)
+#define PCLK_DIV_60 (CTRL_CR1 | CTRL_CR2)
+#define BCLK_DIV_8 (CTRL_CR0 | CTRL_CR1 | CTRL_CR2)
+#define CLK_MASK (CTRL_CR0 | CTRL_CR1 | CTRL_CR2)
+
+/**
+ * struct mchp_corei2c_dev - Microchip CoreI2C device private data
+ *
+ * @base: pointer to register struct
+ * @dev: device reference
+ * @i2c_clk: clock reference for i2c input clock
+ * @buf: pointer to msg buffer for easier use
+ * @msg_complete: xfer completion object
+ * @adapter: core i2c abstraction
+ * @msg_err: error code for completed message
+ * @bus_clk_rate: current i2c bus clock rate
+ * @isr_status: cached copy of local ISR status
+ * @msg_len: number of bytes transferred in msg
+ * @addr: address of the current slave
+ */
+struct mchp_corei2c_dev {
+ void __iomem *base;
+ struct device *dev;
+ struct clk *i2c_clk;
+ u8 *buf;
+ struct completion msg_complete;
+ struct i2c_adapter adapter;
+ int msg_err;
+ u32 bus_clk_rate;
+ u32 isr_status;
+ u16 msg_len;
+ u8 addr;
+};
+
+static void mchp_corei2c_core_disable(struct mchp_corei2c_dev *idev)
+{
+ u8 ctrl = readb(idev->base + CORE_I2C_CTRL);
+
+ ctrl &= ~CTRL_ENS1;
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+}
+
+static void mchp_corei2c_core_enable(struct mchp_corei2c_dev *idev)
+{
+ u8 ctrl = readb(idev->base + CORE_I2C_CTRL);
+
+ ctrl |= CTRL_ENS1;
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+}
+
+static void mchp_corei2c_reset(struct mchp_corei2c_dev *idev)
+{
+ mchp_corei2c_core_disable(idev);
+ mchp_corei2c_core_enable(idev);
+}
+
+static inline void mchp_corei2c_stop(struct mchp_corei2c_dev *idev)
+{
+ u8 ctrl = readb(idev->base + CORE_I2C_CTRL);
+
+ ctrl |= CTRL_STO;
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+}
+
+static inline int mchp_corei2c_set_divisor(u32 rate,
+ struct mchp_corei2c_dev *idev)
+{
+ u8 clkval, ctrl;
+
+ if (rate >= 960)
+ clkval = PCLK_DIV_960;
+ else if (rate >= 256)
+ clkval = PCLK_DIV_256;
+ else if (rate >= 224)
+ clkval = PCLK_DIV_224;
+ else if (rate >= 192)
+ clkval = PCLK_DIV_192;
+ else if (rate >= 160)
+ clkval = PCLK_DIV_160;
+ else if (rate >= 120)
+ clkval = PCLK_DIV_120;
+ else if (rate >= 60)
+ clkval = PCLK_DIV_60;
+ else if (rate >= 8)
+ clkval = BCLK_DIV_8;
+ else
+ return -EINVAL;
+
+ ctrl = readb(idev->base + CORE_I2C_CTRL);
+ ctrl &= ~CLK_MASK;
+ ctrl |= clkval;
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+
+ ctrl = readb(idev->base + CORE_I2C_CTRL);
+ if ((ctrl & CLK_MASK) != clkval)
+ return -EIO;
+
+ return 0;
+}
+
+static int mchp_corei2c_init(struct mchp_corei2c_dev *idev)
+{
+ u32 clk_rate = clk_get_rate(idev->i2c_clk);
+ u32 divisor = clk_rate / idev->bus_clk_rate;
+ int ret;
+
+ ret = mchp_corei2c_set_divisor(divisor, idev);
+ if (ret)
+ return ret;
+
+ mchp_corei2c_reset(idev);
+
+ return 0;
+}
+
+static void mchp_corei2c_empty_rx(struct mchp_corei2c_dev *idev)
+{
+ u8 ctrl;
+
+ if (idev->msg_len > 0) {
+ *idev->buf++ = readb(idev->base + CORE_I2C_DATA);
+ idev->msg_len--;
+ }
+
+ if (idev->msg_len == 0) {
+ ctrl = readb(idev->base + CORE_I2C_CTRL);
+ ctrl &= ~CTRL_AA;
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+ }
+}
+
+static int mchp_corei2c_fill_tx(struct mchp_corei2c_dev *idev)
+{
+ if (idev->msg_len > 0)
+ writeb(*idev->buf++, idev->base + CORE_I2C_DATA);
+ idev->msg_len--;
+
+ return 0;
+}
+
+static irqreturn_t mchp_corei2c_handle_isr(struct mchp_corei2c_dev *idev)
+{
+ u32 status = idev->isr_status;
+ u8 ctrl;
+ bool last_byte = false, finished = false;
+
+ if (!idev->buf)
+ return IRQ_NONE;
+
+ switch (status) {
+ case STATUS_M_START_SENT:
+ case STATUS_M_REPEATED_START_SENT:
+ ctrl = readb(idev->base + CORE_I2C_CTRL);
+ ctrl &= ~CTRL_STA;
+ writeb(idev->addr, idev->base + CORE_I2C_DATA);
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+ if (idev->msg_len == 0)
+ finished = true;
+ break;
+ case STATUS_M_ARB_LOST:
+ idev->msg_err = -EAGAIN;
+ finished = true;
+ break;
+ case STATUS_M_SLAW_ACK:
+ case STATUS_M_TX_DATA_ACK:
+ if (idev->msg_len > 0)
+ mchp_corei2c_fill_tx(idev);
+ else
+ last_byte = true;
+ break;
+ case STATUS_M_TX_DATA_NACK:
+ case STATUS_M_SLAR_NACK:
+ case STATUS_M_SLAW_NACK:
+ idev->msg_err = -ENXIO;
+ last_byte = true;
+ break;
+ case STATUS_M_SLAR_ACK:
+ ctrl = readb(idev->base + CORE_I2C_CTRL);
+ if (idev->msg_len == 1u) {
+ ctrl &= ~CTRL_AA;
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+ } else {
+ ctrl |= CTRL_AA;
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+ }
+ if (idev->msg_len < 1u)
+ last_byte = true;
+ break;
+ case STATUS_M_RX_DATA_ACKED:
+ mchp_corei2c_empty_rx(idev);
+ break;
+ case STATUS_M_RX_DATA_NACKED:
+ mchp_corei2c_empty_rx(idev);
+ if (idev->msg_len == 0)
+ last_byte = true;
+ break;
+ default:
+ break;
+ }
+
+ /* On the last byte to be transmitted, send STOP */
+ if (last_byte)
+ mchp_corei2c_stop(idev);
+
+ if (last_byte || finished)
+ complete(&idev->msg_complete);
+
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t mchp_corei2c_isr(int irq, void *_dev)
+{
+ struct mchp_corei2c_dev *idev = _dev;
+ irqreturn_t ret = IRQ_NONE;
+ u8 ctrl;
+
+ ctrl = readb(idev->base + CORE_I2C_CTRL);
+ if (ctrl & CTRL_SI) {
+ idev->isr_status = readb(idev->base + CORE_I2C_STATUS);
+ ret = mchp_corei2c_handle_isr(idev);
+ }
+
+ ctrl = readb(idev->base + CORE_I2C_CTRL);
+ ctrl &= ~CTRL_SI;
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+
+ return ret;
+}
+
+static int mchp_corei2c_xfer_msg(struct mchp_corei2c_dev *idev,
+ struct i2c_msg *msg)
+{
+ u8 ctrl;
+ unsigned long time_left;
+
+ idev->addr = i2c_8bit_addr_from_msg(msg);
+ idev->msg_len = msg->len;
+ idev->buf = msg->buf;
+ idev->msg_err = 0;
+
+ reinit_completion(&idev->msg_complete);
+
+ mchp_corei2c_core_enable(idev);
+
+ ctrl = readb(idev->base + CORE_I2C_CTRL);
+ ctrl |= CTRL_STA;
+ writeb(ctrl, idev->base + CORE_I2C_CTRL);
+
+ time_left = wait_for_completion_timeout(&idev->msg_complete,
+ idev->adapter.timeout);
+ if (!time_left)
+ return -ETIMEDOUT;
+
+ return idev->msg_err;
+}
+
+static int mchp_corei2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+ int num)
+{
+ struct mchp_corei2c_dev *idev = i2c_get_adapdata(adap);
+ int i, ret;
+
+ for (i = 0; i < num; i++) {
+ ret = mchp_corei2c_xfer_msg(idev, msgs++);
+ if (ret)
+ return ret;
+ }
+
+ return num;
+}
+
+static u32 mchp_corei2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm mchp_corei2c_algo = {
+ .master_xfer = mchp_corei2c_xfer,
+ .functionality = mchp_corei2c_func,
+};
+
+static int mchp_corei2c_probe(struct platform_device *pdev)
+{
+ struct mchp_corei2c_dev *idev;
+ struct resource *res;
+ int irq, ret;
+
+ idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL);
+ if (!idev)
+ return -ENOMEM;
+
+ idev->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+ if (IS_ERR(idev->base))
+ return PTR_ERR(idev->base);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq <= 0)
+ return dev_err_probe(&pdev->dev, -ENXIO,
+ "invalid IRQ %d for I2C controller\n", irq);
+
+ idev->i2c_clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(idev->i2c_clk))
+ return dev_err_probe(&pdev->dev, PTR_ERR(idev->i2c_clk),
+ "missing clock\n");
+
+ idev->dev = &pdev->dev;
+ init_completion(&idev->msg_complete);
+
+ ret = device_property_read_u32(idev->dev, "clock-frequency",
+ &idev->bus_clk_rate);
+ if (ret || !idev->bus_clk_rate) {
+ dev_info(&pdev->dev, "default to 100kHz\n");
+ idev->bus_clk_rate = 100000;
+ }
+
+ if (idev->bus_clk_rate > 400000)
+ return dev_err_probe(&pdev->dev, -EINVAL,
+ "clock-frequency too high: %d\n",
+ idev->bus_clk_rate);
+
+ /*
+ * This driver supports both the hard peripherals & soft FPGA cores.
+ * The hard peripherals do not have shared IRQs, but we don't have
+ * control over what way the interrupts are wired for the soft cores.
+ */
+ ret = devm_request_irq(&pdev->dev, irq, mchp_corei2c_isr, IRQF_SHARED,
+ pdev->name, idev);
+ if (ret)
+ return dev_err_probe(&pdev->dev, ret,
+ "failed to claim irq %d\n", irq);
+
+ ret = clk_prepare_enable(idev->i2c_clk);
+ if (ret)
+ return dev_err_probe(&pdev->dev, ret,
+ "failed to enable clock\n");
+
+ ret = mchp_corei2c_init(idev);
+ if (ret) {
+ clk_disable_unprepare(idev->i2c_clk);
+ return dev_err_probe(&pdev->dev, ret, "failed to program clock divider\n");
+ }
+
+ i2c_set_adapdata(&idev->adapter, idev);
+ snprintf(idev->adapter.name, sizeof(idev->adapter.name),
+ "Microchip I2C hw bus at %08lx", (unsigned long)res->start);
+ idev->adapter.owner = THIS_MODULE;
+ idev->adapter.algo = &mchp_corei2c_algo;
+ idev->adapter.dev.parent = &pdev->dev;
+ idev->adapter.dev.of_node = pdev->dev.of_node;
+ idev->adapter.timeout = HZ;
+
+ platform_set_drvdata(pdev, idev);
+
+ ret = i2c_add_adapter(&idev->adapter);
+ if (ret) {
+ clk_disable_unprepare(idev->i2c_clk);
+ return ret;
+ }
+
+ dev_info(&pdev->dev, "registered CoreI2C bus driver\n");
+
+ return 0;
+}
+
+static int mchp_corei2c_remove(struct platform_device *pdev)
+{
+ struct mchp_corei2c_dev *idev = platform_get_drvdata(pdev);
+
+ clk_disable_unprepare(idev->i2c_clk);
+ i2c_del_adapter(&idev->adapter);
+
+ return 0;
+}
+
+static const struct of_device_id mchp_corei2c_of_match[] = {
+ { .compatible = "microchip,mpfs-i2c" },
+ { .compatible = "microchip,corei2c-rtl-v7" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, mchp_corei2c_of_match);
+
+static struct platform_driver mchp_corei2c_driver = {
+ .probe = mchp_corei2c_probe,
+ .remove = mchp_corei2c_remove,
+ .driver = {
+ .name = "microchip-corei2c",
+ .of_match_table = mchp_corei2c_of_match,
+ },
+};
+
+module_platform_driver(mchp_corei2c_driver);
+
+MODULE_DESCRIPTION("Microchip CoreI2C bus driver");
+MODULE_AUTHOR("Daire McNamara <daire.mcnamara@microchip.com>");
+MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
+MODULE_LICENSE("GPL");

base-commit: 088b9c375534d905a4d337c78db3b3bfbb52c4a0
--
2.36.1