diff options
| author | Codrin Ciubotariu <codrin.ciubotariu@microchip.com> | 2020-02-25 18:50:09 +0300 |
|---|---|---|
| committer | Wolfram Sang <wsa@kernel.org> | 2020-05-05 17:37:21 +0300 |
| commit | 73371d5f313aa056a451f84b652623da6054f89b (patch) | |
| tree | 1052e339cc6101cf65a6ecc55823a160ad35cb3a /drivers/i2c/busses/i2c-at91-master.c | |
| parent | e896be5ad1017aa710f8b979036a43d3e5b2f38d (diff) | |
| download | linux-73371d5f313aa056a451f84b652623da6054f89b.tar.xz | |
i2c: at91: Send bus clear command if SDA is down
After a transfer timeout, some faulty I2C slave devices might hold down
the SDA pin. We can generate a bus clear command, hoping that the slave
might release the pins.
If the CLEAR command is not supported, we will use gpio recovery, if
available, to reset the bus.
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Diffstat (limited to 'drivers/i2c/busses/i2c-at91-master.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-at91-master.c | 49 |
1 files changed, 42 insertions, 7 deletions
diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c index 0aba51a7df32..776e95962ab6 100644 --- a/drivers/i2c/busses/i2c-at91-master.c +++ b/drivers/i2c/busses/i2c-at91-master.c @@ -480,7 +480,6 @@ 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 @@ -641,11 +640,12 @@ error: 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); - } + /* + * some faulty I2C slave devices might hold SDA down; + * we can send a bus clear command, hoping that the pins will be + * released + */ + i2c_recover_bus(&dev->adapter); return ret; } @@ -830,7 +830,7 @@ static void at91_unprepare_twi_recovery(struct i2c_adapter *adap) pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_default); } -static int at91_init_twi_recovery_info(struct platform_device *pdev, +static int at91_init_twi_recovery_gpio(struct platform_device *pdev, struct at91_twi_dev *dev) { struct i2c_bus_recovery_info *rinfo = &dev->rinfo; @@ -880,6 +880,41 @@ static int at91_init_twi_recovery_info(struct platform_device *pdev, return 0; } +static int at91_twi_recover_bus_cmd(struct i2c_adapter *adap) +{ + struct at91_twi_dev *dev = i2c_get_adapdata(adap); + + dev->transfer_status |= at91_twi_read(dev, AT91_TWI_SR); + if (!(dev->transfer_status & AT91_TWI_SDA)) { + dev_dbg(dev->dev, "SDA is down; sending bus clear command\n"); + if (dev->use_alt_cmd) { + unsigned int acr; + + acr = at91_twi_read(dev, AT91_TWI_ACR); + acr &= ~AT91_TWI_ACR_DATAL_MASK; + at91_twi_write(dev, AT91_TWI_ACR, acr); + } + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_CLEAR); + } + + return 0; +} + +static int at91_init_twi_recovery_info(struct platform_device *pdev, + struct at91_twi_dev *dev) +{ + struct i2c_bus_recovery_info *rinfo = &dev->rinfo; + bool has_clear_cmd = dev->pdata->has_clear_cmd; + + if (!has_clear_cmd) + return at91_init_twi_recovery_gpio(pdev, dev); + + rinfo->recover_bus = at91_twi_recover_bus_cmd; + 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) { |