From 24cb07b0c0724a22e474d12e7c2d5b834bf3b076 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Tue, 26 Mar 2024 15:57:46 +0000 Subject: [PATCH 0998/1085] i2c: designware: Add support for bus clear feature Newer versions of the DesignWare I2C block support the detection of stuck signals, and a mechanism to recover from them. Add the required software support to the driver. This change was prompted by the observation that reading a single byte from register 0 of a VEML7700 seems to cause it to issue an ACK too early, and the controller to complain about losing arbitration. There is a suspicion that this may be a more widespread problem, but at least this patch prevents the bus from locking up. See: https://github.com/raspberrypi/linux/issues/6057 Signed-off-by: Phil Elwell --- drivers/i2c/busses/i2c-designware-common.c | 12 ++++++++++++ drivers/i2c/busses/i2c-designware-core.h | 8 ++++++++ drivers/i2c/busses/i2c-designware-master.c | 19 ++++++++++++++++++- 3 files changed, 38 insertions(+), 1 deletion(-) --- a/drivers/i2c/busses/i2c-designware-common.c +++ b/drivers/i2c/busses/i2c-designware-common.c @@ -57,6 +57,8 @@ static char *abort_sources[] = { "slave lost the bus while transmitting data to a remote master", [ABRT_SLAVE_RD_INTX] = "incorrect slave-transmitter mode configuration", + [ABRT_SLAVE_SDA_STUCK_AT_LOW] = + "SDA stuck at low", }; static int dw_reg_read(void *context, unsigned int reg, unsigned int *val) @@ -607,8 +609,16 @@ int i2c_dw_wait_bus_not_busy(struct dw_i int i2c_dw_handle_tx_abort(struct dw_i2c_dev *dev) { unsigned long abort_source = dev->abort_source; + unsigned int reg; int i; + if (abort_source & DW_IC_TX_ABRT_SLAVE_SDA_STUCK_AT_LOW) { + regmap_write(dev->map, DW_IC_ENABLE, + DW_IC_ENABLE_ENABLE | DW_IC_ENABLE_BUS_RECOVERY); + regmap_read_poll_timeout(dev->map, DW_IC_ENABLE, reg, + !(reg & DW_IC_ENABLE_BUS_RECOVERY), + 1100, 200000); + } if (abort_source & DW_IC_TX_ABRT_NOACK) { for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources)) dev_dbg(dev->dev, @@ -623,6 +633,8 @@ int i2c_dw_handle_tx_abort(struct dw_i2c return -EAGAIN; else if (abort_source & DW_IC_TX_ABRT_GCALL_READ) return -EINVAL; /* wrong msgs[] data */ + else if (abort_source & DW_IC_TX_ABRT_SLAVE_SDA_STUCK_AT_LOW) + return -EREMOTEIO; else return -EIO; } --- a/drivers/i2c/busses/i2c-designware-core.h +++ b/drivers/i2c/busses/i2c-designware-core.h @@ -79,9 +79,12 @@ #define DW_IC_TX_ABRT_SOURCE 0x80 #define DW_IC_ENABLE_STATUS 0x9c #define DW_IC_CLR_RESTART_DET 0xa8 +#define DW_IC_SCL_STUCK_AT_LOW_TIMEOUT 0xac +#define DW_IC_SDA_STUCK_AT_LOW_TIMEOUT 0xb0 #define DW_IC_COMP_PARAM_1 0xf4 #define DW_IC_COMP_VERSION 0xf8 #define DW_IC_SDA_HOLD_MIN_VERS 0x3131312A /* "111*" == v1.11* */ +#define DW_IC_BUS_CLEAR_MIN_VERS 0x3230302A /* "200*" == v2.00* */ #define DW_IC_COMP_TYPE 0xfc #define DW_IC_COMP_TYPE_VALUE 0x44570140 /* "DW" + 0x0140 */ @@ -111,12 +114,14 @@ #define DW_IC_ENABLE_ENABLE BIT(0) #define DW_IC_ENABLE_ABORT BIT(1) +#define DW_IC_ENABLE_BUS_RECOVERY BIT(3) #define DW_IC_STATUS_ACTIVITY BIT(0) #define DW_IC_STATUS_TFE BIT(2) #define DW_IC_STATUS_RFNE BIT(3) #define DW_IC_STATUS_MASTER_ACTIVITY BIT(5) #define DW_IC_STATUS_SLAVE_ACTIVITY BIT(6) +#define DW_IC_STATUS_SDA_STUCK_NOT_RECOVERED BIT(11) #define DW_IC_SDA_HOLD_RX_SHIFT 16 #define DW_IC_SDA_HOLD_RX_MASK GENMASK(23, 16) @@ -164,6 +169,7 @@ #define ABRT_SLAVE_FLUSH_TXFIFO 13 #define ABRT_SLAVE_ARBLOST 14 #define ABRT_SLAVE_RD_INTX 15 +#define ABRT_SLAVE_SDA_STUCK_AT_LOW 17 #define DW_IC_TX_ABRT_7B_ADDR_NOACK BIT(ABRT_7B_ADDR_NOACK) #define DW_IC_TX_ABRT_10ADDR1_NOACK BIT(ABRT_10ADDR1_NOACK) @@ -179,6 +185,7 @@ #define DW_IC_RX_ABRT_SLAVE_RD_INTX BIT(ABRT_SLAVE_RD_INTX) #define DW_IC_RX_ABRT_SLAVE_ARBLOST BIT(ABRT_SLAVE_ARBLOST) #define DW_IC_RX_ABRT_SLAVE_FLUSH_TXFIFO BIT(ABRT_SLAVE_FLUSH_TXFIFO) +#define DW_IC_TX_ABRT_SLAVE_SDA_STUCK_AT_LOW BIT(ABRT_SLAVE_SDA_STUCK_AT_LOW) #define DW_IC_TX_ABRT_NOACK (DW_IC_TX_ABRT_7B_ADDR_NOACK | \ DW_IC_TX_ABRT_10ADDR1_NOACK | \ --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -212,6 +212,7 @@ static int i2c_dw_set_timings_master(str */ static int i2c_dw_init_master(struct dw_i2c_dev *dev) { + unsigned int timeout = 0; int ret; ret = i2c_dw_acquire_lock(dev); @@ -235,6 +236,17 @@ static int i2c_dw_init_master(struct dw_ regmap_write(dev->map, DW_IC_HS_SCL_LCNT, dev->hs_lcnt); } + if (dev->master_cfg & DW_IC_CON_BUS_CLEAR_CTRL) { + /* Set a sensible timeout if not already configured */ + regmap_read(dev->map, DW_IC_SDA_STUCK_AT_LOW_TIMEOUT, &timeout); + if (timeout == ~0) { + /* Use 10ms as a timeout, which is 1000 cycles at 100kHz */ + timeout = i2c_dw_clk_rate(dev) * 10; /* clock rate is in kHz */ + regmap_write(dev->map, DW_IC_SDA_STUCK_AT_LOW_TIMEOUT, timeout); + regmap_write(dev->map, DW_IC_SCL_STUCK_AT_LOW_TIMEOUT, timeout); + } + } + /* Write SDA hold time if supported */ if (dev->sda_hold_time) regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time); @@ -1071,6 +1083,7 @@ int i2c_dw_probe_master(struct dw_i2c_de struct i2c_adapter *adap = &dev->adapter; unsigned long irq_flags; unsigned int ic_con; + unsigned int id_ver; int ret; init_completion(&dev->cmd_complete); @@ -1106,7 +1119,11 @@ int i2c_dw_probe_master(struct dw_i2c_de if (ret) return ret; - if (ic_con & DW_IC_CON_BUS_CLEAR_CTRL) + ret = regmap_read(dev->map, DW_IC_COMP_VERSION, &id_ver); + if (ret) + return ret; + + if (ic_con & DW_IC_CON_BUS_CLEAR_CTRL || id_ver >= DW_IC_BUS_CLEAR_MIN_VERS) dev->master_cfg |= DW_IC_CON_BUS_CLEAR_CTRL; ret = dev->init(dev);