From: Zbigniew Bodek <z...@semihalf.com>
All the Armada XP (mv78230, mv78260 and mv78460) have a silicon issue
in the I2C controller which violate the i2c repeated start
timing. The I2C standard requires a minimum of 4.7us for the repeated
start condition whereas the I2C controller of the Armada XP this time
is 2.9us.
So this patch adds a 5us delay for the start case only if the
mv64xxx_i2c_errata_delay flag is set.
[gregory.clem...@free-electrons.com: Merge the incoming commits into
this single one]
[gregory.clem...@free-electrons.com: Reword the commit log]
Signed-off-by: Gregory CLEMENT <gregory.clem...@free-electrons.com>
Signed-off-by: Zbigniew Bodek <z...@semihalf.com>
---
drivers/i2c/busses/i2c-mv64xxx.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 1a3abd6..60cac9f 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -23,6 +23,7 @@
#include <linux/of_i2c.h>
#include <linux/clk.h>
#include <linux/err.h>
+#include <linux/delay.h>
/* Register defines */
#define MV64XXX_I2C_REG_SLAVE_ADDR 0x00
@@ -59,6 +60,12 @@
#define MV64XXX_I2C_STATUS_MAST_RD_ADDR_2_NO_ACK 0xe8
#define MV64XXX_I2C_STATUS_NO_STATUS 0xf8
+/*
+ * 5us delay in order to avoid repeated start
+ * timing violation on Armada XP SoC.
+ */
+static int mv64xxx_i2c_errata_delay;
+
/* Driver states */
enum {
MV64XXX_I2C_STATE_INVALID,
@@ -252,6 +259,9 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
writel(drv_data->cntl_bits,
drv_data->reg_base + MV64XXX_I2C_REG_CONTROL);
drv_data->block = 0;
+ if (mv64xxx_i2c_errata_delay)
+ udelay(5);
+
wake_up(&drv_data->waitq);
break;
@@ -300,6 +310,9 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
writel(drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_STOP,
drv_data->reg_base + MV64XXX_I2C_REG_CONTROL);
drv_data->block = 0;
+ if (mv64xxx_i2c_errata_delay)
+ udelay(5);
+
wake_up(&drv_data->waitq);
break;
@@ -592,6 +605,10 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
* So hard code the value to 1 second.
*/
drv_data->adapter.timeout = HZ;
+
+ if (!mv64xxx_i2c_errata_delay &&
+ of_machine_is_compatible("marvell,armadaxp"))
+ mv64xxx_i2c_errata_delay = 1;
out:
return rc;
#endif
--
1.8.1.2
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
