[PATCH v2 2/2] i2c: Add Renesas RZ/V2M controller

[Phil Edworthy <phil.edworthy@renesas.com>]

Yet another i2c controller from Renesas that is found on the RZ/V2M
(r9a09g011) SoC. It can support only 100kHz and 400KHz operation.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
---
v2:
 - Use the new NOIRQ_SYSTEM_SLEEP_PM_OPS() as suggested by Arnd
 - Lots of small fixes based on Geert's review
---
 drivers/i2c/busses/Kconfig     |  10 +
 drivers/i2c/busses/Makefile    |   1 +
 drivers/i2c/busses/i2c-rzv2m.c | 530 +++++++++++++++++++++++++++++++++
 3 files changed, 541 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-rzv2m.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index b1d7069dd377..9e3f9eb1ea3c 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -984,6 +984,16 @@ config I2C_RK3X
 	  This driver can also be built as a module. If so, the module will
 	  be called i2c-rk3x.
 
+config I2C_RZV2M
+	tristate "Renesas RZ/V2M adapter"
+	depends on ARCH_RENESAS || COMPILE_TEST
+	help
+	  If you say yes to this option, support will be included for the
+	  Renesas RZ/V2M  I2C interface.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-rzv2m.
+
 config I2C_S3C2410
 	tristate "S3C/Exynos I2C Driver"
 	depends on ARCH_EXYNOS || ARCH_S3C24XX || ARCH_S3C64XX || \
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index b0a10e5d9ee9..7792ffc591f0 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -101,6 +101,7 @@ obj-$(CONFIG_I2C_QCOM_GENI)	+= i2c-qcom-geni.o
 obj-$(CONFIG_I2C_QUP)		+= i2c-qup.o
 obj-$(CONFIG_I2C_RIIC)		+= i2c-riic.o
 obj-$(CONFIG_I2C_RK3X)		+= i2c-rk3x.o
+obj-$(CONFIG_I2C_RZV2M)		+= i2c-rzv2m.o
 obj-$(CONFIG_I2C_S3C2410)	+= i2c-s3c2410.o
 obj-$(CONFIG_I2C_SH7760)	+= i2c-sh7760.o
 obj-$(CONFIG_I2C_SH_MOBILE)	+= i2c-sh_mobile.o
diff --git a/drivers/i2c/busses/i2c-rzv2m.c b/drivers/i2c/busses/i2c-rzv2m.c
new file mode 100644
index 000000000000..ab326d557dc5
--- /dev/null
+++ b/drivers/i2c/busses/i2c-rzv2m.c
@@ -0,0 +1,530 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for the Renesas RZ/V2M I2C unit
+ *
+ * Copyright (C) 2016-2022 Renesas Electronics Corporation
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/i2c.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+
+/* Register offsets */
+#define IICB0DAT	0x00		/* Data Register */
+#define IICB0CTL0	0x08		/* Control Register 0 */
+#define IICB0TRG	0x0C		/* Trigger Register */
+#define IICB0STR0	0x10		/* Status Register 0 */
+#define IICB0CTL1	0x20		/* Control Register 1 */
+#define IICB0WL		0x24		/* Low Level Width Setting Reg */
+#define IICB0WH		0x28		/* How Level Width Setting Reg */
+
+/* IICB0CTL0 */
+#define IICB0IICE	BIT(7)		/* I2C Enable */
+#define IICB0SLWT	BIT(1)		/* Interrupt Request Timing */
+#define IICB0SLAC	BIT(0)		/* Acknowledge */
+
+/* IICB0TRG */
+#define IICB0WRET	BIT(2)		/* Quit Wait Trigger */
+#define IICB0STT	BIT(1)		/* Create Start Condition Trigger */
+#define IICB0SPT	BIT(0)		/* Create Stop Condition Trigger */
+
+/* IICB0STR0 */
+#define IICB0SSAC	BIT(8)		/* Ack Flag */
+#define IICB0SSBS	BIT(6)		/* Bus Flag */
+#define IICB0SSSP	BIT(4)		/* Stop Condition Flag */
+
+/* IICB0CTL1 */
+#define IICB0MDSC	BIT(7)		/* Bus Mode */
+#define IICB0SLSE	BIT(1)		/* Start condition output */
+
+#define rzv2m_i2c_priv_to_dev(p)	((p)->adap.dev.parent)
+
+#define bit_setl(addr, val)		writel(readl(addr) | (val), (addr))
+#define bit_clrl(addr, val)		writel(readl(addr) & ~(val), (addr))
+
+struct rzv2m_i2c_priv {
+	void __iomem *base;
+	struct i2c_adapter adap;
+	struct clk *clk;
+	int bus_mode;
+	struct completion msg_tia_done;
+	u32 iicb0wl;
+	u32 iicb0wh;
+};
+
+enum bcr_index {
+	RZV2M_I2C_100K = 0,
+	RZV2M_I2C_400K,
+};
+
+struct bitrate_config {
+	unsigned int percent_low;
+	unsigned int min_hold_time_ns;
+};
+
+static const struct bitrate_config bitrate_configs[] = {
+	[RZV2M_I2C_100K] = { 47, 3450 },
+	[RZV2M_I2C_400K] = { 52, 900},
+};
+
+static irqreturn_t rzv2m_i2c_tia_irq_handler(int this_irq, void *dev_id)
+{
+	struct rzv2m_i2c_priv *priv = dev_id;
+
+	complete(&priv->msg_tia_done);
+
+	return IRQ_HANDLED;
+}
+
+/* Calculate IICB0WL and IICB0WH */
+static int rzv2m_i2c_clock_calculate(struct device *dev,
+				     struct rzv2m_i2c_priv *priv)
+{
+	const struct bitrate_config *config;
+	unsigned int hold_time_ns;
+	unsigned int total_pclks;
+	unsigned int trf_pclks;
+	unsigned long pclk_hz;
+	struct i2c_timings t;
+	u32 trf_ns;
+
+	i2c_parse_fw_timings(dev, &t, true);
+
+	pclk_hz = clk_get_rate(priv->clk);
+	total_pclks = pclk_hz / t.bus_freq_hz;
+
+	trf_ns = t.scl_rise_ns + t.scl_fall_ns;
+	trf_pclks = mul_u64_u32_div(pclk_hz, trf_ns, NSEC_PER_SEC);
+
+	/* Config setting */
+	switch (t.bus_freq_hz) {
+	case I2C_MAX_FAST_MODE_FREQ:
+		priv->bus_mode = RZV2M_I2C_400K;
+		break;
+	case I2C_MAX_STANDARD_MODE_FREQ:
+		priv->bus_mode = RZV2M_I2C_100K;
+		break;
+	default:
+		dev_err(dev, "transfer speed is invalid\n");
+		return -EINVAL;
+	}
+	config = &bitrate_configs[priv->bus_mode];
+
+	/* IICB0WL = (percent_low / Transfer clock) x PCLK */
+	priv->iicb0wl = total_pclks * config->percent_low / 100;
+	if (priv->iicb0wl > 0x3ff)
+		return -EINVAL;
+
+	/* IICB0WH = ((percent_high / Transfer clock) x PCLK) - (tR + tF) */
+	priv->iicb0wh = total_pclks - priv->iicb0wl - trf_pclks;
+	if (priv->iicb0wh > 0x3ff)
+		return -EINVAL;
+
+	/*
+	 * Data hold time must be less than 0.9us in fast mode and
+	 * 3.45us in standard mode.
+	 * Data hold time = IICB0WL[9:2] / PCLK
+	 */
+	hold_time_ns = div64_ul((u64)(priv->iicb0wl >> 2) * NSEC_PER_SEC, pclk_hz);
+	if (hold_time_ns > config->min_hold_time_ns) {
+		dev_err(dev, "data hold time %dns is over %dns\n",
+			hold_time_ns, config->min_hold_time_ns);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void rzv2m_i2c_init(struct rzv2m_i2c_priv *priv)
+{
+	u32 i2c_ctl0;
+	u32 i2c_ctl1;
+
+	/* i2c disable */
+	writel(0, priv->base + IICB0CTL0);
+
+	/* IICB0CTL1 setting */
+	i2c_ctl1 = IICB0SLSE;
+	if (priv->bus_mode == RZV2M_I2C_400K)
+		i2c_ctl1 |= IICB0MDSC;
+	writel(i2c_ctl1, priv->base + IICB0CTL1);
+
+	/* IICB0WL IICB0WH setting */
+	writel(priv->iicb0wl, priv->base + IICB0WL);
+	writel(priv->iicb0wh, priv->base + IICB0WH);
+
+	/* i2c enable after setting */
+	i2c_ctl0 = IICB0SLWT | IICB0SLAC | IICB0IICE;
+	writel(i2c_ctl0, priv->base + IICB0CTL0);
+}
+
+static int rzv2m_i2c_write_with_ack(struct rzv2m_i2c_priv *priv, u32 data)
+{
+	unsigned long time_left;
+
+	reinit_completion(&priv->msg_tia_done);
+
+	writel(data, priv->base + IICB0DAT);
+
+	time_left = wait_for_completion_timeout(&priv->msg_tia_done,
+						priv->adap.timeout);
+	if (!time_left)
+		return -ETIMEDOUT;
+
+	/* Confirm ACK */
+	if ((readl(priv->base + IICB0STR0) & IICB0SSAC) != IICB0SSAC)
+		return -ENXIO;
+
+	return 0;
+}
+
+static int rzv2m_i2c_read_with_ACK(struct rzv2m_i2c_priv *priv, u8 *data,
+				   bool last)
+{
+	unsigned long time_left;
+	u32 data_tmp;
+
+	reinit_completion(&priv->msg_tia_done);
+
+	/* Interrupt request timing : 8th clock */
+	bit_clrl(priv->base + IICB0CTL0, IICB0SLWT);
+
+	/* Exit the wait state */
+	writel(IICB0WRET, priv->base + IICB0TRG);
+
+	/* Wait for transaction */
+	time_left = wait_for_completion_timeout(&priv->msg_tia_done,
+						priv->adap.timeout);
+	if (!time_left)
+		return -ETIMEDOUT;
+
+	if (!last) {
+		/* Read data */
+		data_tmp = readl(priv->base + IICB0DAT);
+	} else {
+		/* Disable ACK */
+		bit_clrl(priv->base + IICB0CTL0, IICB0SLAC);
+
+		/* Read data*/
+		data_tmp = readl(priv->base + IICB0DAT);
+
+		/* Interrupt request timing : 9th clock */
+		bit_setl(priv->base + IICB0CTL0, IICB0SLWT);
+
+		/* Exit the wait state */
+		writel(IICB0WRET, priv->base + IICB0TRG);
+
+		/* Wait for transaction */
+		time_left = wait_for_completion_timeout(&priv->msg_tia_done,
+							priv->adap.timeout);
+		if (!time_left)
+			return -ETIMEDOUT;
+
+		/* Enable ACK */
+		bit_setl(priv->base + IICB0CTL0, IICB0SLAC);
+	}
+
+	*data = data_tmp;
+
+	return 0;
+}
+
+static int rzv2m_i2c_send(struct rzv2m_i2c_priv *priv, struct i2c_msg *msg,
+			  unsigned int *count)
+{
+	unsigned int i;
+	int ret = 0;
+
+	for (i = 0; i < msg->len; i++) {
+		ret = rzv2m_i2c_write_with_ack(priv, msg->buf[i]);
+		if (ret < 0)
+			return ret;
+	}
+	*count = i;
+
+	return ret;
+}
+
+static int rzv2m_i2c_receive(struct rzv2m_i2c_priv *priv, struct i2c_msg *msg,
+			     unsigned int *count)
+{
+	unsigned int i;
+	int ret = 0;
+
+	for (i = 0; i < msg->len; i++) {
+		ret = rzv2m_i2c_read_with_ACK(priv, &msg->buf[i],
+					      ((msg->len - 1) == i));
+		if (ret < 0)
+			return ret;
+	}
+	*count = i;
+
+	return ret;
+}
+
+static int rzv2m_i2c_send_address(struct rzv2m_i2c_priv *priv,
+				  struct i2c_msg *msg)
+{
+	u32 addr;
+	int ret;
+
+	if (msg->flags & I2C_M_TEN) {
+		/* 10-bit address
+		 *   addr_1: 5'b11110 | addr[9:8] | (R/nW)
+		 *   addr_2: addr[7:0]
+		 */
+		addr = 0xf0 | ((msg->addr >> 7) & 0x06);
+		addr |= !!(msg->flags & I2C_M_RD);
+		/* Send 1st address(extend code) */
+		ret = rzv2m_i2c_write_with_ack(priv, addr);
+		if (ret == 0) {
+			/* Send 2nd address */
+			ret = rzv2m_i2c_write_with_ack(priv, msg->addr & 0xff);
+		}
+	} else {
+		/* 7-bit address */
+		addr = i2c_8bit_addr_from_msg(msg);
+		ret = rzv2m_i2c_write_with_ack(priv, addr);
+	}
+
+	return ret;
+}
+
+static int rzv2m_i2c_stop_condition(struct rzv2m_i2c_priv *priv)
+{
+	u32 value;
+
+	/* Send stop condition */
+	writel(IICB0SPT, priv->base + IICB0TRG);
+	return readl_poll_timeout(priv->base + IICB0STR0,
+				  value, value & IICB0SSSP,
+				  100, jiffies_to_usecs(priv->adap.timeout));
+}
+
+static int rzv2m_i2c_master_xfer1(struct rzv2m_i2c_priv *priv,
+				  struct i2c_msg *msg, int stop)
+{
+	unsigned int count = 0;
+	int ret, read = !!(msg->flags & I2C_M_RD);
+
+	/* Send start condition */
+	writel(IICB0STT, priv->base + IICB0TRG);
+
+	ret = rzv2m_i2c_send_address(priv, msg);
+	if (ret == 0) {
+		if (read)
+			ret = rzv2m_i2c_receive(priv, msg, &count);
+		else
+			ret = rzv2m_i2c_send(priv, msg, &count);
+
+		if ((ret == 0) && stop)
+			ret = rzv2m_i2c_stop_condition(priv);
+	}
+
+	if (ret == -ENXIO)
+		rzv2m_i2c_stop_condition(priv);
+	else if (ret < 0)
+		rzv2m_i2c_init(priv);
+	else
+		ret = count;
+
+	return ret;
+}
+
+static int rzv2m_i2c_master_xfer(struct i2c_adapter *adap,
+				 struct i2c_msg *msgs, int num)
+{
+	struct rzv2m_i2c_priv *priv = i2c_get_adapdata(adap);
+	struct device *dev = rzv2m_i2c_priv_to_dev(priv);
+	unsigned int i;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret < 0)
+		return ret;
+
+	if (readl(priv->base + IICB0STR0) & IICB0SSBS) {
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	/* I2C main transfer */
+	for (i = 0; i < num; i++) {
+		ret = rzv2m_i2c_master_xfer1(priv, &msgs[i], (i == (num - 1)));
+		if (ret < 0)
+			goto out;
+	}
+	ret = num;
+
+out:
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
+	return ret;
+}
+
+static u32 rzv2m_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
+	       I2C_FUNC_10BIT_ADDR;
+}
+
+static const struct i2c_adapter_quirks rzv2m_i2c_quirks = {
+	.flags = I2C_AQ_NO_ZERO_LEN,
+};
+
+static struct i2c_algorithm rzv2m_i2c_algo = {
+	.master_xfer = rzv2m_i2c_master_xfer,
+	.functionality = rzv2m_i2c_func,
+};
+
+static const struct of_device_id rzv2m_i2c_ids[] = {
+	{ .compatible = "renesas,rzv2m-i2c", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, rzv2m_i2c_ids);
+
+static int rzv2m_i2c_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rzv2m_i2c_priv *priv;
+	struct reset_control *rstc;
+	struct i2c_adapter *adap;
+	struct resource *res;
+	int irq, ret;
+
+	priv = devm_kzalloc(dev, sizeof(struct rzv2m_i2c_priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err_probe(dev, PTR_ERR(priv->clk), "Can't get clock\n");
+		return PTR_ERR(priv->clk);
+	}
+
+	rstc = devm_reset_control_get(dev, NULL);
+	if (IS_ERR(rstc)) {
+		dev_err_probe(dev, PTR_ERR(rstc), "Missing reset ctrl\n");
+		return PTR_ERR(rstc);
+	}
+	/*
+	 * The reset also affects other HW that is not under the control
+	 * of Linux. Therefore, all we can do is deassert the reset.
+	 */
+	reset_control_deassert(rstc);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	ret = devm_request_irq(dev, irq, rzv2m_i2c_tia_irq_handler, 0,
+			       dev_name(dev), priv);
+	if (ret < 0) {
+		dev_err_probe(dev, ret, "Unable to request irq %d\n", irq);
+		return ret;
+	}
+
+	adap = &priv->adap;
+	adap->nr = pdev->id;
+	adap->algo = &rzv2m_i2c_algo;
+	adap->quirks = &rzv2m_i2c_quirks;
+	adap->class = I2C_CLASS_DEPRECATED;
+	adap->dev.parent = dev;
+	adap->dev.of_node = dev->of_node;
+	adap->owner = THIS_MODULE;
+	i2c_set_adapdata(adap, priv);
+	strscpy(adap->name, pdev->name, sizeof(adap->name));
+	init_completion(&priv->msg_tia_done);
+
+	ret = rzv2m_i2c_clock_calculate(dev, priv);
+	if (ret < 0)
+		return ret;
+
+	pm_runtime_enable(dev);
+
+	pm_runtime_get_sync(dev);
+	rzv2m_i2c_init(priv);
+	pm_runtime_put(dev);
+
+	platform_set_drvdata(pdev, priv);
+
+	ret = i2c_add_numbered_adapter(adap);
+	if (ret < 0)
+		pm_runtime_disable(dev);
+
+	return ret;
+}
+
+static int rzv2m_i2c_remove(struct platform_device *pdev)
+{
+	struct rzv2m_i2c_priv *priv = platform_get_drvdata(pdev);
+	struct device *dev = rzv2m_i2c_priv_to_dev(priv);
+
+	i2c_del_adapter(&priv->adap);
+	bit_clrl(priv->base + IICB0CTL0, IICB0IICE);
+	pm_runtime_disable(dev);
+
+	return 0;
+}
+
+static int rzv2m_i2c_suspend(struct device *dev)
+{
+	struct rzv2m_i2c_priv *priv = dev_get_drvdata(dev);
+
+	pm_runtime_get_sync(dev);
+	bit_clrl(priv->base + IICB0CTL0, IICB0IICE);
+	pm_runtime_put(dev);
+
+	return 0;
+}
+
+static int rzv2m_i2c_resume(struct device *dev)
+{
+	struct rzv2m_i2c_priv *priv = dev_get_drvdata(dev);
+	int ret;
+
+	ret = rzv2m_i2c_clock_calculate(dev, priv);
+	if (ret < 0)
+		return ret;
+
+	pm_runtime_get_sync(dev);
+	rzv2m_i2c_init(priv);
+	pm_runtime_put(dev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops rzv2m_i2c_pm_ops = {
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(rzv2m_i2c_suspend, rzv2m_i2c_resume)
+};
+
+static struct platform_driver rzv2m_i2c_driver = {
+	.driver = {
+		.name = "rzv2m-i2c",
+		.of_match_table = rzv2m_i2c_ids,
+		.pm = pm_sleep_ptr(&rzv2m_i2c_pm_ops),
+	},
+	.probe	= rzv2m_i2c_probe,
+	.remove	= rzv2m_i2c_remove,
+};
+module_platform_driver(rzv2m_i2c_driver);
+
+MODULE_DESCRIPTION("RZ/V2M I2C bus driver");
+MODULE_AUTHOR("Renesas Electronics Corporation");
+MODULE_LICENSE("GPL");
-- 
2.34.1