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 | |
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>
-rw-r--r-- | drivers/i2c/busses/i2c-at91-core.c | 2 | ||||
-rw-r--r-- | drivers/i2c/busses/i2c-at91-master.c | 49 | ||||
-rw-r--r-- | drivers/i2c/busses/i2c-at91.h | 7 |
3 files changed, 50 insertions, 8 deletions
diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c index 3da1a8acecb5..e14edd236108 100644 --- a/drivers/i2c/busses/i2c-at91-core.c +++ b/drivers/i2c/busses/i2c-at91-core.c @@ -131,6 +131,7 @@ static struct at91_twi_pdata sama5d2_config = { .has_dig_filtr = true, .has_adv_dig_filtr = true, .has_ana_filtr = true, + .has_clear_cmd = false, /* due to errata, CLEAR cmd is not working */ }; static struct at91_twi_pdata sam9x60_config = { @@ -142,6 +143,7 @@ static struct at91_twi_pdata sam9x60_config = { .has_dig_filtr = true, .has_adv_dig_filtr = true, .has_ana_filtr = true, + .has_clear_cmd = true, }; static const struct of_device_id atmel_twi_dt_ids[] = { 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) { diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h index f57a6cab96b4..7e7b4955ca7f 100644 --- a/drivers/i2c/busses/i2c-at91.h +++ b/drivers/i2c/busses/i2c-at91.h @@ -36,6 +36,7 @@ #define AT91_TWI_SVDIS BIT(5) /* Slave Transfer Disable */ #define AT91_TWI_QUICK BIT(6) /* SMBus quick command */ #define AT91_TWI_SWRST BIT(7) /* Software Reset */ +#define AT91_TWI_CLEAR BIT(15) /* Bus clear command */ #define AT91_TWI_ACMEN BIT(16) /* Alternative Command Mode Enable */ #define AT91_TWI_ACMDIS BIT(17) /* Alternative Command Mode Disable */ #define AT91_TWI_THRCLR BIT(24) /* Transmit Holding Register Clear */ @@ -69,6 +70,8 @@ #define AT91_TWI_NACK BIT(8) /* Not Acknowledged */ #define AT91_TWI_EOSACC BIT(11) /* End Of Slave Access */ #define AT91_TWI_LOCK BIT(23) /* TWI Lock due to Frame Errors */ +#define AT91_TWI_SCL BIT(24) /* TWI SCL status */ +#define AT91_TWI_SDA BIT(25) /* TWI SDA status */ #define AT91_TWI_INT_MASK \ (AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK \ @@ -81,7 +84,8 @@ #define AT91_TWI_THR 0x0034 /* Transmit Holding Register */ #define AT91_TWI_ACR 0x0040 /* Alternative Command Register */ -#define AT91_TWI_ACR_DATAL(len) ((len) & 0xff) +#define AT91_TWI_ACR_DATAL_MASK GENMASK(15, 0) +#define AT91_TWI_ACR_DATAL(len) ((len) & AT91_TWI_ACR_DATAL_MASK) #define AT91_TWI_ACR_DIR BIT(8) #define AT91_TWI_FILTR 0x0044 @@ -118,6 +122,7 @@ struct at91_twi_pdata { bool has_dig_filtr; bool has_adv_dig_filtr; bool has_ana_filtr; + bool has_clear_cmd; struct at_dma_slave dma_slave; }; |