From 659aa30c59fb188b533a7edcb9bd38ac007a2739 Mon Sep 17 00:00:00 2001
From: Yangbo Lu <yangbo.lu@nxp.com>
Date: Wed, 17 Jan 2018 15:35:11 +0800
Subject: [PATCH 21/30] i2c: support layerscape

This is an integrated patch for layerscape i2c support.

Signed-off-by: Zhang Ying-22455 <ying.zhang22455@nxp.com>
Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
---
 drivers/i2c/busses/i2c-imx.c        | 195 +++++++++++++++++++++++++++++++++++-
 drivers/i2c/muxes/i2c-mux-pca954x.c |  43 ++++++++
 2 files changed, 237 insertions(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -53,6 +53,11 @@
 #include <linux/pm_runtime.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
+#include <linux/gpio.h>
+#include <linux/of_address.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/libata.h>
 
 /* This will be the driver name the kernel reports */
 #define DRIVER_NAME "imx-i2c"
@@ -117,6 +122,54 @@
 
 #define I2C_PM_TIMEOUT		10 /* ms */
 
+enum pinmux_endian_type {
+	BIG_ENDIAN,
+	LITTLE_ENDIAN,
+};
+
+struct pinmux_cfg {
+	enum pinmux_endian_type endian; /* endian of RCWPMUXCR0 */
+	u32 pmuxcr_offset;
+	u32 pmuxcr_set_bit;		    /* pin mux of RCWPMUXCR0 */
+};
+
+static struct pinmux_cfg ls1012a_pinmux_cfg = {
+	.endian = BIG_ENDIAN,
+	.pmuxcr_offset = 0x430,
+	.pmuxcr_set_bit = 0x10,
+};
+
+static struct pinmux_cfg ls1043a_pinmux_cfg = {
+	.endian = BIG_ENDIAN,
+	.pmuxcr_offset = 0x40C,
+	.pmuxcr_set_bit = 0x10,
+};
+
+static struct pinmux_cfg ls1046a_pinmux_cfg = {
+	.endian = BIG_ENDIAN,
+	.pmuxcr_offset = 0x40C,
+	.pmuxcr_set_bit = 0x80000000,
+};
+
+static const struct of_device_id pinmux_of_match[] = {
+	{ .compatible = "fsl,ls1012a-vf610-i2c", .data = &ls1012a_pinmux_cfg},
+	{ .compatible = "fsl,ls1043a-vf610-i2c", .data = &ls1043a_pinmux_cfg},
+	{ .compatible = "fsl,ls1046a-vf610-i2c", .data = &ls1046a_pinmux_cfg},
+	{},
+};
+MODULE_DEVICE_TABLE(of, pinmux_of_match);
+
+/* The SCFG, Supplemental Configuration Unit, provides SoC specific
+ * configuration and status registers for the device. There is a
+ * SDHC IO VSEL control register on SCFG for some platforms. It's
+ * used to support SDHC IO voltage switching.
+ */
+static const struct of_device_id scfg_device_ids[] = {
+	{ .compatible = "fsl,ls1012a-scfg", },
+	{ .compatible = "fsl,ls1043a-scfg", },
+	{ .compatible = "fsl,ls1046a-scfg", },
+	{}
+};
 /*
  * sorted list of clock divider, register value pairs
  * taken from table 26-5, p.26-9, Freescale i.MX
@@ -210,6 +263,12 @@ struct imx_i2c_struct {
 	struct pinctrl_state *pinctrl_pins_gpio;
 
 	struct imx_i2c_dma	*dma;
+	int			layerscape_bus_recover;
+	int 			gpio;
+	int			need_set_pmuxcr;
+	int			pmuxcr_set;
+	int			pmuxcr_endian;
+	void __iomem		*pmuxcr_addr;
 };
 
 static const struct imx_i2c_hwdata imx1_i2c_hwdata = {
@@ -878,6 +937,78 @@ static int i2c_imx_read(struct imx_i2c_s
 	return 0;
 }
 
+/*
+ * Based on the I2C specification, if the data line (SDA) is
+ * stuck low, the master should send nine  * clock pulses.
+ * The I2C slave device that held the bus low should release it
+ * sometime within  * those nine clocks. Due to this erratum,
+ * the I2C controller cannot generate nine clock pulses.
+ */
+static int i2c_imx_recovery_for_layerscape(struct imx_i2c_struct *i2c_imx)
+{
+	u32 pmuxcr = 0;
+	int ret;
+	unsigned int i, temp;
+
+	/* configure IICx_SCL/GPIO pin as a GPIO */
+	if (i2c_imx->need_set_pmuxcr == 1) {
+		pmuxcr = ioread32be(i2c_imx->pmuxcr_addr);
+		if (i2c_imx->pmuxcr_endian == BIG_ENDIAN)
+			iowrite32be(i2c_imx->pmuxcr_set|pmuxcr,
+				    i2c_imx->pmuxcr_addr);
+		else
+			iowrite32(i2c_imx->pmuxcr_set|pmuxcr,
+				  i2c_imx->pmuxcr_addr);
+	}
+
+	ret = gpio_request(i2c_imx->gpio, i2c_imx->adapter.name);
+	if (ret) {
+		dev_err(&i2c_imx->adapter.dev,
+			"can't get gpio: %d\n", ret);
+		return ret;
+	}
+
+	/* Configure GPIO pin as an output and open drain. */
+	gpio_direction_output(i2c_imx->gpio, 1);
+	udelay(10);
+
+	/* Write data to generate 9 pulses */
+	for (i = 0; i < 9; i++) {
+		gpio_set_value(i2c_imx->gpio, 1);
+		udelay(10);
+		gpio_set_value(i2c_imx->gpio, 0);
+		udelay(10);
+	}
+	/* ensure that the last level sent is always high */
+	gpio_set_value(i2c_imx->gpio, 1);
+
+	/*
+	 * Set I2Cx_IBCR = 0h00 to generate a STOP and then
+	 * set I2Cx_IBCR = 0h80 to reset
+	 */
+	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+	temp &= ~(I2CR_MSTA | I2CR_MTX);
+	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+	/* Restore the saved value of the register SCFG_RCWPMUXCR0 */
+	if (i2c_imx->need_set_pmuxcr == 1) {
+		if (i2c_imx->pmuxcr_endian == BIG_ENDIAN)
+			iowrite32be(pmuxcr, i2c_imx->pmuxcr_addr);
+		else
+			iowrite32(pmuxcr, i2c_imx->pmuxcr_addr);
+	}
+	/*
+	 * Set I2C_IBSR[IBAL] to clear the IBAL bit if-
+	 * I2C_IBSR[IBAL] = 1
+	 */
+	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
+	if (temp & I2SR_IAL) {
+		temp &= ~I2SR_IAL;
+		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
+	}
+	return 0;
+}
+
 static int i2c_imx_xfer(struct i2c_adapter *adapter,
 						struct i2c_msg *msgs, int num)
 {
@@ -888,6 +1019,19 @@ static int i2c_imx_xfer(struct i2c_adapt
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 
+	/*
+	 * workround for ERR010027: ensure that the I2C BUS is idle
+	 * before switching to master mode and attempting a Start cycle
+	 */
+	result =  i2c_imx_bus_busy(i2c_imx, 0);
+	if (result) {
+		/* timeout */
+		if ((result == -ETIMEDOUT) && (i2c_imx->layerscape_bus_recover == 1))
+			i2c_imx_recovery_for_layerscape(i2c_imx);
+		else
+			goto out;
+	}
+
 	result = pm_runtime_get_sync(i2c_imx->adapter.dev.parent);
 	if (result < 0)
 		goto out;
@@ -1030,6 +1174,50 @@ static int i2c_imx_init_recovery_info(st
 	return 0;
 }
 
+/*
+ * switch SCL and SDA to their GPIO function and do some bitbanging
+ * for bus recovery.
+ * There are platforms such as Layerscape that don't support pinctrl, so add
+ * workaround for layerscape, it has no effect for other platforms.
+ */
+static int i2c_imx_init_recovery_for_layerscape(
+		struct imx_i2c_struct *i2c_imx,
+		struct platform_device *pdev)
+{
+	const struct of_device_id *of_id;
+	struct device_node *np		= pdev->dev.of_node;
+	struct pinmux_cfg		*pinmux_cfg;
+	struct device_node *scfg_node;
+	void __iomem *scfg_base = NULL;
+
+	i2c_imx->gpio = of_get_named_gpio(np, "fsl-scl-gpio", 0);
+	if (!gpio_is_valid(i2c_imx->gpio)) {
+		dev_info(&pdev->dev, "fsl-scl-gpio not found\n");
+		return 0;
+	}
+	pinmux_cfg = devm_kzalloc(&pdev->dev, sizeof(*pinmux_cfg), GFP_KERNEL);
+	if (!pinmux_cfg)
+		return -ENOMEM;
+
+	i2c_imx->need_set_pmuxcr = 0;
+	of_id = of_match_node(pinmux_of_match, np);
+	if (of_id) {
+		pinmux_cfg = (struct pinmux_cfg *)of_id->data;
+		i2c_imx->pmuxcr_endian = pinmux_cfg->endian;
+		i2c_imx->pmuxcr_set = pinmux_cfg->pmuxcr_set_bit;
+		scfg_node = of_find_matching_node(NULL, scfg_device_ids);
+		if (scfg_node) {
+			scfg_base = of_iomap(scfg_node, 0);
+			if (scfg_base) {
+				i2c_imx->pmuxcr_addr = scfg_base + pinmux_cfg->pmuxcr_offset;
+				i2c_imx->need_set_pmuxcr = 1;
+			}
+		}
+	}
+	i2c_imx->layerscape_bus_recover = 1;
+	return 0;
+}
+
 static u32 i2c_imx_func(struct i2c_adapter *adapter)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
@@ -1085,6 +1273,11 @@ static int i2c_imx_probe(struct platform
 	i2c_imx->adapter.dev.of_node	= pdev->dev.of_node;
 	i2c_imx->base			= base;
 
+	/* Init optional bus recovery for layerscape */
+	ret = i2c_imx_init_recovery_for_layerscape(i2c_imx, pdev);
+	if (ret)
+		return ret;
+
 	/* Get I2C clock */
 	i2c_imx->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(i2c_imx->clk)) {
@@ -1100,7 +1293,7 @@ static int i2c_imx_probe(struct platform
 	}
 
 	/* Request IRQ */
-	ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, 0,
+	ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, IRQF_SHARED,
 				pdev->name, i2c_imx);
 	if (ret) {
 		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -74,6 +74,7 @@ struct pca954x {
 	u8 last_chan;		/* last register value */
 	u8 deselect;
 	struct i2c_client *client;
+	u8 disable_mux;		/* do not disable mux if val not 0 */
 };
 
 /* Provide specs for the PCA954x types we know about */
@@ -196,6 +197,13 @@ static int pca954x_deselect_mux(struct i
 	if (!(data->deselect & (1 << chan)))
 		return 0;
 
+#ifdef CONFIG_ARCH_LAYERSCAPE
+	if (data->disable_mux != 0)
+		data->last_chan = data->chip->nchans;
+	else
+		data->last_chan = 0;
+	return pca954x_reg_write(muxc->parent, client, data->disable_mux);
+#endif
 	/* Deselect active channel */
 	data->last_chan = 0;
 	return pca954x_reg_write(muxc->parent, client, data->last_chan);
@@ -228,6 +236,28 @@ static int pca954x_probe(struct i2c_clie
 		return -ENOMEM;
 	data = i2c_mux_priv(muxc);
 
+#ifdef CONFIG_ARCH_LAYERSCAPE
+	/* The point here is that you must not disable a mux if there
+	 * are no pullups on the input or you mess up the I2C. This
+	 * needs to be put into the DTS really as the kernel cannot
+	 * know this otherwise.
+	 */
+	match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
+	if (match)
+		data->chip = of_device_get_match_data(&client->dev);
+	else
+		data->chip = &chips[id->driver_data];
+
+	data->disable_mux = of_node &&
+		of_property_read_bool(of_node, "i2c-mux-never-disable") &&
+		data->chip->muxtype == pca954x_ismux ?
+		data->chip->enable : 0;
+	/* force the first selection */
+	if (data->disable_mux != 0)
+		data->last_chan = data->chip->nchans;
+	else
+		data->last_chan = 0;
+#endif
 	i2c_set_clientdata(client, muxc);
 	data->client = client;
 
@@ -240,11 +270,16 @@ static int pca954x_probe(struct i2c_clie
 	 * that the mux is in fact present. This also
 	 * initializes the mux to disconnected state.
 	 */
+#ifdef CONFIG_ARCH_LAYERSCAPE
+	if (i2c_smbus_write_byte(client, data->disable_mux) < 0) {
+#else
 	if (i2c_smbus_write_byte(client, 0) < 0) {
+#endif
 		dev_warn(&client->dev, "probe failed\n");
 		return -ENODEV;
 	}
 
+#ifndef CONFIG_ARCH_LAYERSCAPE
 	match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
 	if (match)
 		data->chip = of_device_get_match_data(&client->dev);
@@ -252,6 +287,7 @@ static int pca954x_probe(struct i2c_clie
 		data->chip = &chips[id->driver_data];
 
 	data->last_chan = 0;		   /* force the first selection */
+#endif
 
 	idle_disconnect_dt = of_node &&
 		of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
@@ -312,6 +348,13 @@ static int pca954x_resume(struct device
 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 	struct pca954x *data = i2c_mux_priv(muxc);
 
+#ifdef CONFIG_ARCH_LAYERSCAPE
+	if (data->disable_mux != 0)
+		data->last_chan = data->chip->nchans;
+	else
+		data->last_chan = 0;
+	return i2c_smbus_write_byte(client, data->disable_mux);
+#endif
 	data->last_chan = 0;
 	return i2c_smbus_write_byte(client, 0);
 }
