[PATCH v1 3/5] i2c: Add Microchip PolarFire SoC I2C driver

[Padmarao Begari <padmarao.begari@microchip.com>]

Add I2C driver code for the Microchip PolarFire SoC.
This driver supports I2C data transfer and probe for I2C
slave addresses.

Signed-off-by: Padmarao Begari <padmarao.begari@microchip.com>
---
 drivers/i2c/Kconfig         |   6 +
 drivers/i2c/Makefile        |   1 +
 drivers/i2c/i2c-microchip.c | 482 ++++++++++++++++++++++++++++++++++++
 3 files changed, 489 insertions(+)
 create mode 100644 drivers/i2c/i2c-microchip.c

diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 7c447a8aa0..5482a4a470 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -250,6 +250,12 @@ config SYS_I2C_MESON
 	  internal buffer holding up to 8 bytes for transfers and supports
 	  both 7-bit and 10-bit addresses.
 
+config SYS_I2C_MICROCHIP
+	bool "Microchip I2C driver"
+	help
+	  Add support for the Microchip I2C driver. This is operating on
+	  standard mode up to 100 kbits/s and fast mode up to 400 kbits/s.
+
 config SYS_I2C_MXC
 	bool "NXP MXC I2C driver"
 	help
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index fca6b157f8..9d41f379bb 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_SYS_I2C_IPROC) += iproc_i2c.o
 obj-$(CONFIG_SYS_I2C_KONA) += kona_i2c.o
 obj-$(CONFIG_SYS_I2C_LPC32XX) += lpc32xx_i2c.o
 obj-$(CONFIG_SYS_I2C_MESON) += meson_i2c.o
+obj-$(CONFIG_SYS_I2C_MICROCHIP) += i2c-microchip.o
 obj-$(CONFIG_SYS_I2C_MV) += mv_i2c.o
 obj-$(CONFIG_SYS_I2C_MVTWSI) += mvtwsi.o
 obj-$(CONFIG_SYS_I2C_MXC) += mxc_i2c.o
diff --git a/drivers/i2c/i2c-microchip.c b/drivers/i2c/i2c-microchip.c
new file mode 100644
index 0000000000..12f65d0af7
--- /dev/null
+++ b/drivers/i2c/i2c-microchip.c
@@ -0,0 +1,482 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Microchip I2C controller driver
+ *
+ * Copyright (C) 2021 Microchip Technology Inc.
+ * Padmarao Begari <padmarao.begari@microchip.com>
+ */
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <i2c.h>
+#include <asm/io.h>
+#include <dm/device_compat.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+
+#define	MICROCHIP_I2C_TIMEOUT	(1000 * 60)
+
+#define MPFS_I2C_CTRL	(0x00)
+#define	CTRL_CR0		(0x00)
+#define	CTRL_CR1		(0x01)
+#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		(0x07)
+#define MPFS_I2C_STATUS							(0x04)
+#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)
+#define	STATUS_NO_STATE_INFO					(0xF8)
+#define MPFS_I2C_DATA			(0x08)
+#define MPFS_I2C_SLAVE0_ADDR	(0x0c)
+#define MPFS_I2C_SMBUS			(0x10)
+#define MPFS_I2C_FREQ			(0x14)
+#define MPFS_I2C_GLITCHREG		(0x18)
+#define MPFS_I2C_SLAVE1_ADDR	(0x1c)
+
+#define PCLK_DIV_256	((0 << CTRL_CR0) | (0 << CTRL_CR1) | (0 << CTRL_CR2))
+#define PCLK_DIV_224	((1 << CTRL_CR0) | (0 << CTRL_CR1) | (0 << CTRL_CR2))
+#define PCLK_DIV_192	((0 << CTRL_CR0) | (1 << CTRL_CR1) | (0 << CTRL_CR2))
+#define PCLK_DIV_160	((1 << CTRL_CR0) | (1 << CTRL_CR1) | (0 << CTRL_CR2))
+#define PCLK_DIV_960	((0 << CTRL_CR0) | (0 << CTRL_CR1) | (1 << CTRL_CR2))
+#define PCLK_DIV_120	((1 << CTRL_CR0) | (0 << CTRL_CR1) | (1 << CTRL_CR2))
+#define PCLK_DIV_60		((0 << CTRL_CR0) | (1 << CTRL_CR1) | (1 << CTRL_CR2))
+#define BCLK_DIV_8		((1 << CTRL_CR0) | (1 << CTRL_CR1) | (1 << CTRL_CR2))
+#define CLK_MASK		((1 << CTRL_CR0) | (1 << CTRL_CR1) | (1 << CTRL_CR2))
+
+/*
+ * mpfs_i2c_bus - I2C bus context
+ * @base: pointer to register struct
+ * @msg_len: number of bytes transferred in msg
+ * @msg_err: error code for completed message
+ * @i2c_clk: clock reference for i2c input clock
+ * @clk_rate: current i2c bus clock rate
+ * @buf: ptr to msg buffer for easier use.
+ * @addr: i2c address.
+ * @isr_status: cached copy of local ISR status.
+ */
+struct mpfs_i2c_bus {
+	void __iomem *base;
+	size_t msg_len;
+	int msg_err;
+	struct clk i2c_clk;
+	u32 clk_rate;
+	u8 *buf;
+	u8 addr;
+	u32 isr_status;
+};
+
+static inline u8 i2c_8bit_addr_from_msg(const struct i2c_msg *msg)
+{
+	return (msg->addr << 1) | (msg->flags & I2C_M_RD ? 1 : 0);
+}
+
+static void mpfs_i2c_int_clear(struct mpfs_i2c_bus *bus)
+{
+	u8 ctrl = readl(bus->base + MPFS_I2C_CTRL);
+
+	ctrl &= ~CTRL_SI;
+	writel(ctrl, bus->base + MPFS_I2C_CTRL);
+}
+
+static void mpfs_i2c_core_disable(struct mpfs_i2c_bus *bus)
+{
+	u8 ctrl = readl(bus->base + MPFS_I2C_CTRL);
+
+	ctrl &= ~CTRL_ENS1;
+	writel(ctrl, bus->base + MPFS_I2C_CTRL);
+}
+
+static void mpfs_i2c_core_enable(struct mpfs_i2c_bus *bus)
+{
+	u8 ctrl = readl(bus->base + MPFS_I2C_CTRL);
+
+	ctrl |= CTRL_ENS1;
+	writel(ctrl, bus->base + MPFS_I2C_CTRL);
+}
+
+static void mpfs_i2c_reset(struct mpfs_i2c_bus *bus)
+{
+	mpfs_i2c_core_disable(bus);
+	mpfs_i2c_core_enable(bus);
+}
+
+static inline void mpfs_i2c_stop(struct mpfs_i2c_bus *bus)
+{
+	u8 ctrl = readl(bus->base + MPFS_I2C_CTRL);
+
+	ctrl |= CTRL_STO;
+	writel(ctrl, bus->base + MPFS_I2C_CTRL);
+}
+
+static inline int mpfs_generate_divisor(u32 rate, u8 *code)
+{
+	int ret = 0;
+
+	if (rate >= 960)
+		*code = PCLK_DIV_960;
+	else if (rate >= 256)
+		*code = PCLK_DIV_256;
+	else if (rate >= 224)
+		*code = PCLK_DIV_224;
+	else if (rate >= 192)
+		*code = PCLK_DIV_192;
+	else if (rate >= 160)
+		*code = PCLK_DIV_160;
+	else if (rate >= 120)
+		*code = PCLK_DIV_120;
+	else if (rate >= 60)
+		*code = PCLK_DIV_60;
+	else if (rate >= 8)
+		*code = BCLK_DIV_8;
+	else
+		ret = -EINVAL;
+
+	return ret;
+}
+
+static int mpfs_i2c_init(struct mpfs_i2c_bus *bus, struct udevice *dev)
+{
+	u32 clk_rate, divisor;
+	u8 clkval, ctrl;
+	int ret;
+
+	ret = clk_get_by_index(dev, 0, &bus->i2c_clk);
+	if (ret)
+		return -EINVAL;
+
+	ret = clk_enable(&bus->i2c_clk);
+	if (ret)
+		return ret;
+
+	clk_rate = clk_get_rate(&bus->i2c_clk);
+	if (!clk_rate)
+		return -EINVAL;
+
+	clk_free(&bus->i2c_clk);
+
+	divisor = clk_rate / bus->clk_rate;
+
+	ctrl = readl(bus->base + MPFS_I2C_CTRL);
+
+	ctrl &= ~CLK_MASK;
+
+	ret = mpfs_generate_divisor(divisor, &clkval);
+	if (ret)
+		return -EINVAL;
+
+	ctrl |= clkval;
+
+	writel(ctrl, bus->base + MPFS_I2C_CTRL);
+
+	ctrl = readl(bus->base + MPFS_I2C_CTRL);
+
+	/* Reset I2C core */
+	mpfs_i2c_reset(bus);
+
+	return 0;
+}
+
+static void mpfs_i2c_transfer(struct mpfs_i2c_bus *bus, u32 data)
+{
+	if (bus->msg_len > 0)
+		writel(data, bus->base + MPFS_I2C_DATA);
+}
+
+static void mpfs_i2c_empty_rx(struct mpfs_i2c_bus *bus)
+{
+	u8 ctrl;
+	u8 data_read;
+
+	if (bus->msg_len > 0) {
+		data_read = readl(bus->base + MPFS_I2C_DATA);
+		*bus->buf++ = data_read;
+		bus->msg_len--;
+	}
+
+	if (bus->msg_len == 0) {
+		ctrl = readl(bus->base + MPFS_I2C_CTRL);
+		ctrl &= ~CTRL_AA;
+		writel(ctrl, bus->base + MPFS_I2C_CTRL);
+	}
+}
+
+static int mpfs_i2c_fill_tx(struct mpfs_i2c_bus *bus)
+{
+	mpfs_i2c_transfer(bus, *bus->buf++);
+	bus->msg_len--;
+
+	return 0;
+}
+
+static int mpfs_i2c_service_handler(struct mpfs_i2c_bus *bus)
+{
+	bool finish = false;
+	u32 status;
+	u8 ctrl;
+
+	status = bus->isr_status;
+
+	switch (status)	{
+	case STATUS_M_START_SENT:
+	case STATUS_M_REPEATED_START_SENT:
+		ctrl = readl(bus->base + MPFS_I2C_CTRL);
+		ctrl &= ~CTRL_STA;
+		writel(bus->addr, bus->base + MPFS_I2C_DATA);
+		writel(ctrl, bus->base + MPFS_I2C_CTRL);
+		break;
+	case STATUS_M_SLAW_ACK:
+	case STATUS_M_TX_DATA_ACK:
+		if (bus->msg_len > 0) {
+			mpfs_i2c_fill_tx(bus);
+		} else {
+			/* On the last byte to be transmitted, send STOP */
+			mpfs_i2c_stop(bus);
+			finish = true;
+		}
+		break;
+	case STATUS_M_SLAR_ACK:
+		ctrl = readl(bus->base + MPFS_I2C_CTRL);
+		ctrl |= CTRL_AA;
+		writel(ctrl, bus->base + MPFS_I2C_CTRL);
+		if (bus->msg_len == 0) {
+			/* On the last byte to be transmitted, send STOP */
+			mpfs_i2c_stop(bus);
+			finish = true;
+		}
+		break;
+	case STATUS_M_RX_DATA_ACKED:
+		mpfs_i2c_empty_rx(bus);
+		if (bus->msg_len == 0) {
+			/* On the last byte to be transmitted, send STOP */
+			mpfs_i2c_stop(bus);
+			finish = true;
+		}
+		break;
+	case STATUS_M_TX_DATA_NACK:
+	case STATUS_M_RX_DATA_NACKED:
+	case STATUS_M_SLAR_NACK:
+	case STATUS_M_SLAW_NACK:
+		bus->msg_err = -ENXIO;
+		mpfs_i2c_stop(bus);
+		finish = true;
+		break;
+
+	case STATUS_M_ARB_LOST:
+		/* Handle Lost Arbitration */
+		bus->msg_err = -EAGAIN;
+		finish = true;
+		break;
+	default:
+		break;
+	}
+
+	if (finish) {
+		ctrl = readl(bus->base + MPFS_I2C_CTRL);
+		ctrl &= ~CTRL_AA;
+		writel(ctrl, bus->base + MPFS_I2C_CTRL);
+		return 0;
+	}
+
+	return 1;
+}
+
+static int mpfs_i2c_service(struct mpfs_i2c_bus *bus)
+{
+	int ret = 0;
+	int si_bit;
+
+	si_bit = readl(bus->base + MPFS_I2C_CTRL);
+	if (si_bit & CTRL_SI) {
+		bus->isr_status = readl(bus->base + MPFS_I2C_STATUS);
+		ret = mpfs_i2c_service_handler(bus);
+	}
+	/* Clear the si flag */
+	mpfs_i2c_int_clear(bus);
+	si_bit = readl(bus->base + MPFS_I2C_CTRL);
+
+	return ret;
+}
+
+static int mpfs_i2c_check_service_change(struct mpfs_i2c_bus *bus)
+{
+	u8 ctrl;
+	u32 count = 0;
+
+	while (1) {
+		ctrl = readl(bus->base + MPFS_I2C_CTRL);
+		if (ctrl & CTRL_SI)
+			break;
+		udelay(1);
+		count += 1;
+		if (count == MICROCHIP_I2C_TIMEOUT)
+			return -ETIMEDOUT;
+	}
+	return 0;
+}
+
+static int mpfs_i2c_poll_device(struct mpfs_i2c_bus *bus)
+{
+	int ret;
+
+	while (1) {
+		ret = mpfs_i2c_check_service_change(bus);
+		if (ret)
+			return ret;
+
+		ret = mpfs_i2c_service(bus);
+		if (!ret)
+			/* all messages have been transferred */
+			return ret;
+	}
+}
+
+static int mpfs_i2c_xfer_msg(struct mpfs_i2c_bus *bus, struct i2c_msg *msg)
+{
+	u8 ctrl;
+	int ret;
+
+	if (!msg->len || !msg->buf)
+		return -EINVAL;
+
+	bus->addr = i2c_8bit_addr_from_msg(msg);
+	bus->msg_len = msg->len;
+	bus->buf = msg->buf;
+	bus->msg_err = 0;
+
+	mpfs_i2c_core_enable(bus);
+
+	ctrl = readl(bus->base + MPFS_I2C_CTRL);
+
+	ctrl |= CTRL_STA;
+
+	writel(ctrl, bus->base + MPFS_I2C_CTRL);
+
+	ret = mpfs_i2c_poll_device(bus);
+	if (ret)
+		return ret;
+
+	return bus->msg_err;
+}
+
+static int mpfs_i2c_xfer(struct udevice *dev, struct i2c_msg *msgs, int num_msgs)
+{
+	struct mpfs_i2c_bus *bus = dev_get_priv(dev);
+	int idx, ret;
+
+	if (!msgs || !num_msgs)
+		return -EINVAL;
+
+	for (idx = 0; idx < num_msgs; idx++) {
+		ret = mpfs_i2c_xfer_msg(bus, msgs++);
+		if (ret)
+			return ret;
+	}
+
+	return ret;
+}
+
+static int mpfs_i2c_probe_chip(struct udevice *dev, uint addr, uint flags)
+{
+	struct mpfs_i2c_bus *bus = dev_get_priv(dev);
+	int ret;
+	u8 ctrl, reg = 0;
+
+	/*
+	 * Send the chip address and verify that the
+	 * address was <ACK>ed.
+	 */
+	bus->addr = addr << 1 | I2C_M_RD;
+	bus->buf = &reg;
+	bus->msg_len = 0;
+	bus->msg_err = 0;
+
+	mpfs_i2c_core_enable(bus);
+
+	ctrl = readl(bus->base + MPFS_I2C_CTRL);
+
+	ctrl |= CTRL_STA;
+
+	writel(ctrl, bus->base + MPFS_I2C_CTRL);
+
+	ret = mpfs_i2c_poll_device(bus);
+	if (ret)
+		return ret;
+
+	return bus->msg_err;
+}
+
+static int mpfs_i2c_probe(struct udevice *dev)
+{
+	int ret;
+	u32 val;
+	struct mpfs_i2c_bus *bus = dev_get_priv(dev);
+
+	bus->base = dev_read_addr_ptr(dev);
+	if (!bus->base)
+		return -EINVAL;
+
+	val = dev_read_u32(dev, "clock-frequency", &bus->clk_rate);
+	if (val) {
+		printf("Default to 100kHz\n");
+		/* default clock rate */
+		bus->clk_rate = 100000;
+	}
+
+	if (bus->clk_rate > 400000 || bus->clk_rate <= 0) {
+		printf("Invalid clock-frequency %d\n", bus->clk_rate);
+		return -EINVAL;
+	}
+
+	ret = mpfs_i2c_init(bus, dev);
+
+	return ret;
+}
+
+static const struct dm_i2c_ops mpfs_i2c_ops = {
+	.xfer = mpfs_i2c_xfer,
+	.probe_chip = mpfs_i2c_probe_chip,
+};
+
+static const struct udevice_id mpfs_i2c_ids[] = {
+	{.compatible = "microchip,mpfs-i2c"},
+	{}
+};
+
+U_BOOT_DRIVER(mpfs_i2c) = {
+	.name = "mpfs_i2c",
+	.id = UCLASS_I2C,
+	.of_match = mpfs_i2c_ids,
+	.ops = &mpfs_i2c_ops,
+	.probe = mpfs_i2c_probe,
+	.priv_auto = sizeof(struct mpfs_i2c_bus),
+};
-- 
2.25.1