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Subject[PATCH] i2c-designware: add i2c gpio recovery option
Date
This patch contains much input from Phil Reid and has been tested
on Intel/Altera Cyclone V SOC Hardware with Altera GPIO's for the
SCL and SDA GPIO's. I am still a little unsure about the recover
in the timeout case (i2c-designware-core.c:770) as i could not
test this codepath.

Signed-off-by: Tim Sander <tim@krieglstein.org>
---
drivers/i2c/busses/i2c-designware-core.c | 14 ++++-
drivers/i2c/busses/i2c-designware-core.h | 4 ++
drivers/i2c/busses/i2c-designware-platdrv.c | 90 ++++++++++++++++++++++++++++-
3 files changed, 104 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 7a3faa551cf8..f955f29ff8e7 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -317,6 +317,7 @@ static void i2c_dw_release_lock(struct dw_i2c_dev *dev)
dev->release_lock(dev);
}

+
/**
* i2c_dw_init() - initialize the designware i2c master hardware
* @dev: device private data
@@ -463,7 +464,12 @@ static int i2c_dw_wait_bus_not_busy(struct dw_i2c_dev *dev)
while (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY) {
if (timeout <= 0) {
dev_warn(dev->dev, "timeout waiting for bus ready\n");
- return -ETIMEDOUT;
+ i2c_recover_bus(&dev->adapter);
+
+ if (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY)
+ return -ETIMEDOUT;
+ else
+ return 0;
}
timeout--;
usleep_range(1000, 1100);
@@ -719,9 +725,10 @@ static int i2c_dw_handle_tx_abort(struct dw_i2c_dev *dev)
for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources))
dev_err(dev->dev, "%s: %s\n", __func__, abort_sources[i]);

- if (abort_source & DW_IC_TX_ARB_LOST)
+ if (abort_source & DW_IC_TX_ARB_LOST) {
+ i2c_recover_bus(&dev->adapter);
return -EAGAIN;
- else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
+ } else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
return -EINVAL; /* wrong msgs[] data */
else
return -EIO;
@@ -766,6 +773,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
if (!wait_for_completion_timeout(&dev->cmd_complete, adap->timeout)) {
dev_err(dev->dev, "controller timed out\n");
/* i2c_dw_init implicitly disables the adapter */
+ i2c_recover_bus(&dev->adapter);
i2c_dw_init(dev);
ret = -ETIMEDOUT;
goto done;
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index d9aaf1790e0e..cedc895a795d 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -23,6 +23,7 @@
*/

#include <linux/i2c.h>
+#include <linux/gpio.h>

#define DW_IC_DEFAULT_FUNCTIONALITY (I2C_FUNC_I2C | \
I2C_FUNC_SMBUS_BYTE | \
@@ -126,6 +127,9 @@ struct dw_i2c_dev {
int (*acquire_lock)(struct dw_i2c_dev *dev);
void (*release_lock)(struct dw_i2c_dev *dev);
bool pm_runtime_disabled;
+ struct i2c_bus_recovery_info rinfo;
+ struct gpio_desc *gpio_sda;
+ struct gpio_desc *gpio_scl;
};

#define ACCESS_SWAP 0x00000001
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 79c4b4ea0539..b2d5adc8df2b 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -41,6 +41,7 @@
#include <linux/reset.h>
#include <linux/slab.h>
#include <linux/acpi.h>
+#include <linux/of_gpio.h>
#include <linux/platform_data/i2c-designware.h>
#include "i2c-designware-core.h"

@@ -174,6 +175,88 @@ static void dw_i2c_set_fifo_size(struct dw_i2c_dev *dev, int id)
}
}

+/*
+ * This routine does i2c bus recovery by using i2c_generic_gpio_recovery
+ * which is provided by I2C Bus recovery infrastructure.
+ */
+static void i2c_dw_prepare_recovery(struct i2c_adapter *adap)
+{
+ struct platform_device *pdev = to_platform_device(&adap->dev);
+ struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
+
+ i2c_dw_disable(i_dev);
+ reset_control_assert(i_dev->rst);
+ i2c_dw_plat_prepare_clk(i_dev, false);
+}
+
+void i2c_dw_unprepare_recovery(struct i2c_adapter *adap)
+{
+ struct platform_device *pdev = to_platform_device(&adap->dev);
+ struct dw_i2c_dev *i_dev = platform_get_drvdata(pdev);
+
+ i2c_dw_plat_prepare_clk(i_dev, true);
+ reset_control_deassert(i_dev->rst);
+ i2c_dw_init(i_dev);
+}
+
+
+static int i2c_dw_get_scl(struct i2c_adapter *adap)
+{
+ struct platform_device *pdev = to_platform_device(&adap->dev);
+ struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
+
+ return gpiod_get_value_cansleep(dev->gpio_scl);
+}
+
+static void i2c_dw_set_scl(struct i2c_adapter *adap, int val)
+{
+ struct platform_device *pdev = to_platform_device(&adap->dev);
+ struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
+
+ gpiod_set_value_cansleep(dev->gpio_scl, val);
+}
+
+static int i2c_dw_get_sda(struct i2c_adapter *adap)
+{
+ struct platform_device *pdev = to_platform_device(&adap->dev);
+ struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
+
+ return gpiod_get_value_cansleep(dev->gpio_sda);
+}
+
+static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev,
+ struct i2c_adapter *adap)
+{
+ struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
+
+ dev->gpio_scl = devm_gpiod_get_optional(dev->dev,
+ "scl",
+ GPIOD_OUT_HIGH);
+ if (IS_ERR_OR_NULL(dev->gpio_scl))
+ return PTR_ERR(dev->gpio_scl);
+
+ dev->gpio_sda = devm_gpiod_get_optional(dev->dev, "sda", GPIOD_IN);
+ if (IS_ERR_OR_NULL(dev->gpio_sda))
+ return PTR_ERR(dev->gpio_sda);
+
+ rinfo->scl_gpio = desc_to_gpio(dev->gpio_scl);
+ rinfo->sda_gpio = desc_to_gpio(dev->gpio_sda);
+ rinfo->set_scl = i2c_dw_set_scl;
+ rinfo->get_scl = i2c_dw_get_scl;
+ rinfo->get_sda = i2c_dw_get_sda;
+
+ rinfo->recover_bus = i2c_generic_scl_recovery;
+ rinfo->prepare_recovery = i2c_dw_prepare_recovery;
+ rinfo->unprepare_recovery = i2c_dw_unprepare_recovery;
+ adap->bus_recovery_info = rinfo;
+
+ dev_info(dev->dev,
+ "adapter: %s running with gpio recovery mode! scl:%i sda:%i \n",
+ adap->name, rinfo->scl_gpio, rinfo->sda_gpio);
+
+ return 0;
+};
+
static int dw_i2c_plat_probe(struct platform_device *pdev)
{
struct dw_i2c_platform_data *pdata = dev_get_platdata(&pdev->dev);
@@ -285,6 +368,7 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
adap->class = I2C_CLASS_DEPRECATED;
ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
adap->dev.of_node = pdev->dev.of_node;
+ snprintf(adap->name, sizeof(adap->name), "Designware i2c adapter");

if (dev->pm_runtime_disabled) {
pm_runtime_forbid(&pdev->dev);
@@ -295,11 +379,15 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
pm_runtime_enable(&pdev->dev);
}

+ r = i2c_dw_init_recovery_info(dev, adap);
+ if (r == -EPROBE_DEFER)
+ goto exit_probe;
+
r = i2c_dw_probe(dev);
if (r)
goto exit_probe;

- return r;
+ return 0;

exit_probe:
if (!dev->pm_runtime_disabled)
--
2.7.4
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