qup_i2c: Recovery mechanism for GSBI when slave pulls line low
If slave pulls one of the I2C lines low,I2C bus may lock out
failing I2C transactions for all slaves on the GSBI.
Recovery mechanism is added to recover the I2C lines when this
happens. Also, we allow clients to retry when a connection error
is returned.
Change-Id: I12675d828d0880ded292724416b5407427cdf73c
Signed-off-by: Harini Jayaraman <harinij@codeaurora.org>
diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
index 3dbbf15..2d69256 100644
--- a/drivers/i2c/busses/i2c-qup.c
+++ b/drivers/i2c/busses/i2c-qup.c
@@ -29,6 +29,7 @@
#include <linux/timer.h>
#include <linux/slab.h>
#include <mach/board.h>
+#include <mach/gpiomux.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/gpio.h>
@@ -110,6 +111,7 @@
enum {
I2C_STATUS_WR_BUFFER_FULL = 1U << 0,
I2C_STATUS_BUS_ACTIVE = 1U << 8,
+ I2C_STATUS_BUS_MASTER = 1U << 9,
I2C_STATUS_ERROR_MASK = 0x38000FC,
QUP_I2C_NACK_FLAG = 1U << 3,
QUP_IN_NOT_EMPTY = 1U << 5,
@@ -126,6 +128,12 @@
static char const * const i2c_rsrcs[] = {"i2c_clk", "i2c_sda"};
+static struct gpiomux_setting recovery_config = {
+ .func = GPIOMUX_FUNC_GPIO,
+ .drv = GPIOMUX_DRV_8MA,
+ .pull = GPIOMUX_PULL_NONE,
+};
+
struct qup_i2c_dev {
struct device *dev;
void __iomem *base; /* virtual */
@@ -639,6 +647,83 @@
return ret;
}
+
+static void qup_i2c_recover_bus_busy(struct qup_i2c_dev *dev)
+{
+ int i;
+ int gpio_clk;
+ int gpio_dat;
+ bool gpio_clk_status = false;
+ uint32_t status = readl_relaxed(dev->base + QUP_I2C_STATUS);
+ struct gpiomux_setting old_gpio_setting;
+
+ if (dev->pdata->msm_i2c_config_gpio)
+ return;
+
+ if (!(status & (I2C_STATUS_BUS_ACTIVE)) ||
+ (status & (I2C_STATUS_BUS_MASTER)))
+ return;
+
+ gpio_clk = dev->i2c_gpios[0];
+ gpio_dat = dev->i2c_gpios[1];
+
+ if ((gpio_clk == -1) && (gpio_dat == -1)) {
+ dev_err(dev->dev, "Recovery failed due to undefined GPIO's\n");
+ return;
+ }
+
+ disable_irq(dev->err_irq);
+ for (i = 0; i < ARRAY_SIZE(i2c_rsrcs); ++i) {
+ if (msm_gpiomux_write(dev->i2c_gpios[i], GPIOMUX_ACTIVE,
+ &recovery_config, &old_gpio_setting)) {
+ dev_err(dev->dev, "GPIO pins have no active setting\n");
+ goto recovery_end;
+ }
+ }
+
+ dev_warn(dev->dev, "i2c_scl: %d, i2c_sda: %d\n",
+ gpio_get_value(gpio_clk), gpio_get_value(gpio_dat));
+
+ for (i = 0; i < 9; i++) {
+ if (gpio_get_value(gpio_dat) && gpio_clk_status)
+ break;
+ gpio_direction_output(gpio_clk, 0);
+ udelay(5);
+ gpio_direction_output(gpio_dat, 0);
+ udelay(5);
+ gpio_direction_input(gpio_clk);
+ udelay(5);
+ if (!gpio_get_value(gpio_clk))
+ udelay(20);
+ if (!gpio_get_value(gpio_clk))
+ usleep_range(10000, 10000);
+ gpio_clk_status = gpio_get_value(gpio_clk);
+ gpio_direction_input(gpio_dat);
+ udelay(5);
+ }
+
+ /* Configure ALT funciton to QUP I2C*/
+ for (i = 0; i < ARRAY_SIZE(i2c_rsrcs); ++i) {
+ msm_gpiomux_write(dev->i2c_gpios[i], GPIOMUX_ACTIVE,
+ &old_gpio_setting, NULL);
+ }
+
+ udelay(10);
+
+ status = readl_relaxed(dev->base + QUP_I2C_STATUS);
+ if (!(status & I2C_STATUS_BUS_ACTIVE)) {
+ dev_info(dev->dev, "Bus busy cleared after %d clock cycles, "
+ "status %x\n",
+ i, status);
+ goto recovery_end;
+ }
+
+ dev_warn(dev->dev, "Bus still busy, status %x\n", status);
+
+recovery_end:
+ enable_irq(dev->err_irq);
+}
+
static int
qup_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
{
@@ -837,7 +922,8 @@
idx, rem, num, dev->mode);
qup_print_status(dev);
- timeout = wait_for_completion_timeout(&complete, HZ);
+ timeout = wait_for_completion_timeout(&complete,
+ msecs_to_jiffies(dev->out_fifo_sz));
if (!timeout) {
uint32_t istatus = readl_relaxed(dev->base +
QUP_I2C_STATUS);
@@ -846,7 +932,24 @@
uint32_t op_flgs = readl_relaxed(dev->base +
QUP_OPERATIONAL);
- dev_err(dev->dev, "Transaction timed out\n");
+ /*
+ * Dont wait for 1 sec if i2c sees the bus
+ * active and controller is not master.
+ * A slave has pulled line low. Try to recover
+ */
+ if (!(istatus & I2C_STATUS_BUS_ACTIVE) ||
+ (istatus & I2C_STATUS_BUS_MASTER)) {
+ timeout =
+ wait_for_completion_timeout(&complete,
+ HZ);
+ if (timeout)
+ goto timeout_err;
+ }
+ qup_i2c_recover_bus_busy(dev);
+ dev_err(dev->dev,
+ "Transaction timed out, SL-AD = 0x%x\n",
+ dev->msg->addr);
+
dev_err(dev->dev, "I2C Status: %x\n", istatus);
dev_err(dev->dev, "QUP Status: %x\n", qstatus);
dev_err(dev->dev, "OP Flags: %x\n", op_flgs);
@@ -858,17 +961,27 @@
ret = -ETIMEDOUT;
goto out_err;
}
+timeout_err:
if (dev->err) {
if (dev->err > 0 &&
- dev->err & QUP_I2C_NACK_FLAG)
+ dev->err & QUP_I2C_NACK_FLAG) {
dev_err(dev->dev,
"I2C slave addr:0x%x not connected\n",
dev->msg->addr);
- else if (dev->err < 0) {
+ dev->err = ENOTCONN;
+ } else if (dev->err < 0) {
dev_err(dev->dev,
"QUP data xfer error %d\n", dev->err);
ret = dev->err;
goto out_err;
+ } else if (dev->err > 0) {
+ /*
+ * ISR returns +ve error if error code
+ * is I2C related, e.g. unexpected start
+ * So you may call recover-bus-busy when
+ * this error happens
+ */
+ qup_i2c_recover_bus_busy(dev);
}
ret = -dev->err;
goto out_err;