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i2c: mv64xxx: Fix timing issue on Armada XP (errata FE-8471889) 

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
the compatible i2c-mv78230 is set.

Based on the initals patches from Zbigniew Bodek

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Zbigniew Bodek <zbb@semihalf.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Gregory CLEMENT 2013-08-22 16:19:06 +02:00 committed by Wolfram Sang
parent 930ab3d403
commit c1d15b68aa
1 changed files with 13 additions and 2 deletions
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15
drivers/i2c/busses/i2c-mv64xxx.c
View File

@ -24,6 +24,7 @@
#include <linux/of_i2c.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/delay.h>
#define MV64XXX_I2C_ADDR_ADDR(val) ((val & 0x7f) << 1)
#define MV64XXX_I2C_BAUD_DIV_N(val) (val & 0x7)
@ -147,6 +148,8 @@ struct mv64xxx_i2c_data {
struct i2c_msg *msg;
struct i2c_adapter adapter;
bool offload_enabled;
/* 5us delay in order to avoid repeated start timing violation */
bool errata_delay;
};
static struct mv64xxx_i2c_regs mv64xxx_i2c_regs_mv64xxx = {
@ -440,6 +443,9 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
/* Setup for the next message */
mv64xxx_i2c_prepare_for_io(drv_data, drv_data->msgs);
}
if (drv_data->errata_delay)
udelay(5);
/*
* We're never at the start of the message here, and by this
* time it's already too late to do any protocol mangling.
@ -499,6 +505,9 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
writel(drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_STOP,
drv_data->reg_base + drv_data->reg_offsets.control);
drv_data->block = 0;
if (drv_data->errata_delay)
udelay(5);
wake_up(&drv_data->waitq);
break;
@ -766,10 +775,12 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
/*
* For controllers embedded in new SoCs activate the
* Transaction Generator support.
* Transaction Generator support and the errata fix.
*/
if (of_device_is_compatible(np, "marvell,mv78230-i2c"))
if (of_device_is_compatible(np, "marvell,mv78230-i2c")) {
drv_data->offload_enabled = true;
drv_data->errata_delay = true;
}
out:
return rc;