--- /dev/null
+From ddf55be668a5e5a22d4b7729e7ba92d928983168 Mon Sep 17 00:00:00 2001
+From: Zhang Ying-22455 <ying.zhang22455@nxp.com>
+Date: Fri, 1 Dec 2017 15:59:28 +0800
+Subject: [PATCH] i2c: imx: implement bus recovery with gpio for Layerscape
+
+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.
+
+Because pinctrl is not supported on Layerscape, current bus recovery
+is not avalible for Layerscape. This patch uses an open drain GPIO
+pin to connect to the IICx_SCL to drive nine clock pulses to unlock
+the I2C bus.
+
+Signed-off-by: Zhang Ying-22455 <ying.zhang22455@nxp.com>
+---
+ drivers/i2c/busses/i2c-imx.c | 190 ++++++++++++++++++++++++++++++++++++++++++-
+ 1 file changed, 188 insertions(+), 2 deletions(-)
+
+--- a/drivers/i2c/busses/i2c-imx.c
++++ b/drivers/i2c/busses/i2c-imx.c
+@@ -39,12 +39,18 @@
+ #include <linux/of.h>
+ #include <linux/of_device.h>
+ #include <linux/of_dma.h>
++#include <linux/of_gpio.h>
+ #include <linux/pinctrl/consumer.h>
+ #include <linux/platform_data/i2c-imx.h>
+ #include <linux/platform_device.h>
+ #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"
+@@ -110,6 +116,54 @@
+
+ #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
+@@ -205,6 +259,12 @@ 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 = {
+@@ -923,6 +983,78 @@ 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)
+ {
+@@ -945,8 +1077,13 @@ static int i2c_imx_xfer(struct i2c_adapt
+ * before switching to master mode and attempting a Start cycle
+ */
+ result = i2c_imx_bus_busy(i2c_imx, 0);
+- if (result)
+- goto out;
++ 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)
+@@ -1093,6 +1230,50 @@ 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, "scl-gpios", 0);
++ if (!gpio_is_valid(i2c_imx->gpio)) {
++ dev_info(&pdev->dev, "scl-gpios 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
+@@ -1217,8 +1398,13 @@ static int i2c_imx_probe(struct platform
+ i2c_imx, IMX_I2C_I2CR);
+ imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
+
++#ifdef CONFIG_ARCH_LAYERSCAPE
++ /* Init optional bus recovery for layerscape */
++ ret = i2c_imx_init_recovery_for_layerscape(i2c_imx, pdev);
++#else
+ /* Init optional bus recovery function */
+ ret = i2c_imx_init_recovery_info(i2c_imx, pdev);
++#endif
+ /* Give it another chance if pinctrl used is not ready yet */
+ if (ret == -EPROBE_DEFER)
+ goto clk_notifier_unregister;
projects / openwrt / staging / wigyori.git / blobdiff