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i2c: at91: implement i2c bus recovery

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Implement i2c bus recovery when slaves devices might hold SDA low.
In this case re-assign SCL/SDA to gpios and issue 9 dummy clock pulses
until the slave release SDA.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Kamel Bouhara 2020-01-15 13:54:18 +02:00 committed by Wolfram Sang
parent 19e5cef058
commit d3d3fdcc4c
2 changed files with 82 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

78
drivers/i2c/busses/i2c-at91-master.c
View file

@ -18,11 +18,13 @@
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/platform_data/dma-atmel.h>
#include <linux/pm_runtime.h>
@ -478,6 +480,7 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
unsigned long time_left;
bool has_unre_flag = dev->pdata->has_unre_flag;
bool has_alt_cmd = dev->pdata->has_alt_cmd;
struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
/*
* WARNING: the TXCOMP bit in the Status Register is NOT a clear on
@ -637,6 +640,13 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
at91_twi_write(dev, AT91_TWI_CR,
AT91_TWI_THRCLR | AT91_TWI_LOCKCLR);
}
if (rinfo->get_sda && !(rinfo->get_sda(&dev->adapter))) {
dev_dbg(dev->dev,
"SDA is down; clear bus using gpio\n");
i2c_recover_bus(&dev->adapter);
}
return ret;
}
@ -806,6 +816,70 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
return ret;
}
static void at91_prepare_twi_recovery(struct i2c_adapter *adap)
{
struct at91_twi_dev *dev = i2c_get_adapdata(adap);
pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_gpio);
}
static void at91_unprepare_twi_recovery(struct i2c_adapter *adap)
{
struct at91_twi_dev *dev = i2c_get_adapdata(adap);
pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_default);
}
static int at91_init_twi_recovery_info(struct platform_device *pdev,
struct at91_twi_dev *dev)
{
struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
dev->pinctrl = devm_pinctrl_get(&pdev->dev);
if (!dev->pinctrl || IS_ERR(dev->pinctrl)) {
dev_info(dev->dev, "can't get pinctrl, bus recovery not supported\n");
return PTR_ERR(dev->pinctrl);
}
dev->pinctrl_pins_default = pinctrl_lookup_state(dev->pinctrl,
PINCTRL_STATE_DEFAULT);
dev->pinctrl_pins_gpio = pinctrl_lookup_state(dev->pinctrl,
"gpio");
rinfo->sda_gpiod = devm_gpiod_get(&pdev->dev, "sda", GPIOD_IN);
if (PTR_ERR(rinfo->sda_gpiod) == -EPROBE_DEFER)
return -EPROBE_DEFER;
rinfo->scl_gpiod = devm_gpiod_get(&pdev->dev, "scl",
GPIOD_OUT_HIGH_OPEN_DRAIN);
if (PTR_ERR(rinfo->scl_gpiod) == -EPROBE_DEFER)
return -EPROBE_DEFER;
if (IS_ERR(rinfo->sda_gpiod) ||
IS_ERR(rinfo->scl_gpiod) ||
IS_ERR(dev->pinctrl_pins_default) ||
IS_ERR(dev->pinctrl_pins_gpio)) {
dev_info(&pdev->dev, "recovery information incomplete\n");
if (!IS_ERR(rinfo->sda_gpiod)) {
gpiod_put(rinfo->sda_gpiod);
rinfo->sda_gpiod = NULL;
}
if (!IS_ERR(rinfo->scl_gpiod)) {
gpiod_put(rinfo->scl_gpiod);
rinfo->scl_gpiod = NULL;
}
return -EINVAL;
}
dev_info(&pdev->dev, "using scl, sda for recovery\n");
rinfo->prepare_recovery = at91_prepare_twi_recovery;
rinfo->unprepare_recovery = at91_unprepare_twi_recovery;
rinfo->recover_bus = i2c_generic_scl_recovery;
dev->adapter.bus_recovery_info = rinfo;
return 0;
}
int at91_twi_probe_master(struct platform_device *pdev,
u32 phy_addr, struct at91_twi_dev *dev)
{
@ -838,6 +912,10 @@ int at91_twi_probe_master(struct platform_device *pdev,
"i2c-analog-filter");
at91_calc_twi_clock(dev);
rc = at91_init_twi_recovery_info(pdev, dev);
if (rc == -EPROBE_DEFER)
return rc;
dev->adapter.algo = &at91_twi_algorithm;
dev->adapter.quirks = &at91_twi_quirks;

4
drivers/i2c/busses/i2c-at91.h
View file

@ -151,6 +151,10 @@ struct at91_twi_dev {
u32 fifo_size;
struct at91_twi_dma dma;
bool slave_detected;
struct i2c_bus_recovery_info rinfo;
struct pinctrl *pinctrl;
struct pinctrl_state *pinctrl_pins_default;
struct pinctrl_state *pinctrl_pins_gpio;
#ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL
unsigned smr;
struct i2c_client *slave;