| Message ID | 20200115115422.17097-4-codrin.ciubotariu@microchip.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | i2c bus recovery for Microchip SoCs | expand |
On Wed, Jan 15, 2020 at 01:54:19PM +0200, Codrin Ciubotariu wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > 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> I still have issue to apply it even if the context seems correct. Sometimes git am is picky... so Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com> > --- > > Changes in v3: > - rebased on top of i2c/for-next; > - remove unnecessary initializations with false; > - replaced SCL with SDA in title and commit message; > - updated commit message; > > Changes in v2: > - use CLEAR command only if SDA is down; update patch subject to > reflect this; > - CLEAR command is no longer used for sama5d2, only sam9x60; > > drivers/i2c/busses/i2c-at91-core.c | 2 ++ > drivers/i2c/busses/i2c-at91-master.c | 32 +++++++++++++++++++++++----- > drivers/i2c/busses/i2c-at91.h | 7 +++++- > 3 files changed, 35 insertions(+), 6 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..bcc05a8fe826 100644 > --- a/drivers/i2c/busses/i2c-at91-master.c > +++ b/drivers/i2c/busses/i2c-at91-master.c > @@ -480,7 +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; > + bool has_clear_cmd = dev->pdata->has_clear_cmd; > > /* > * WARNING: the TXCOMP bit in the Status Register is NOT a clear on > @@ -641,10 +641,32 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) > 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 > + */ > + if (has_clear_cmd) { > + 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); > + } > + } else { > + struct i2c_bus_recovery_info *rinfo = &dev->rinfo; > + > + 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; > 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; > }; > > -- > 2.20.1 >
On Wed, Jan 15, 2020 at 01:54:19PM +0200, Codrin Ciubotariu wrote: > 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> One thing to improve: > + /* > + * some faulty I2C slave devices might hold SDA down; > + * we can send a bus clear command, hoping that the pins will be > + * released > + */ > + if (has_clear_cmd) { > + 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); > + } The inner if-block should be a seperate function, then you could do in probe: if (has_clear_cmd) rinfo->recover_bus = <the above function>; else rinfo->recover_bus = i2c_generic_scl_recovery; Then, i2c_recover_bus() will always do the right thing. More readable and better maintainable IMO. If this is not possible (maybe I overlooked some logic), then maybe this will work: rinfo->recover_bus = <your custom function>; and put the if (has_clear_cmd) block there.
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..bcc05a8fe826 100644 --- a/drivers/i2c/busses/i2c-at91-master.c +++ b/drivers/i2c/busses/i2c-at91-master.c @@ -480,7 +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; + bool has_clear_cmd = dev->pdata->has_clear_cmd; /* * WARNING: the TXCOMP bit in the Status Register is NOT a clear on @@ -641,10 +641,32 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) 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 + */ + if (has_clear_cmd) { + 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); + } + } else { + struct i2c_bus_recovery_info *rinfo = &dev->rinfo; + + 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; 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; };
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> --- Changes in v3: - rebased on top of i2c/for-next; - remove unnecessary initializations with false; - replaced SCL with SDA in title and commit message; - updated commit message; Changes in v2: - use CLEAR command only if SDA is down; update patch subject to reflect this; - CLEAR command is no longer used for sama5d2, only sam9x60; drivers/i2c/busses/i2c-at91-core.c | 2 ++ drivers/i2c/busses/i2c-at91-master.c | 32 +++++++++++++++++++++++----- drivers/i2c/busses/i2c-at91.h | 7 +++++- 3 files changed, 35 insertions(+), 6 deletions(-)