@@ -37,6 +37,7 @@
#define DW_IC_CON_STOP_DET_IFADDRESSED BIT(7)
#define DW_IC_CON_TX_EMPTY_CTRL BIT(8)
#define DW_IC_CON_RX_FIFO_FULL_HLD_CTRL BIT(9)
+#define DW_IC_CON_BUS_CLEAR_CTRL BIT(11)
#define DW_IC_DATA_CMD_DAT GENMASK(7, 0)
@@ -865,6 +865,7 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
{
struct i2c_adapter *adap = &dev->adapter;
unsigned long irq_flags;
+ u32 ic_con;
int ret;
init_completion(&dev->cmd_complete);
@@ -884,6 +885,24 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
if (ret)
return ret;
+ /*
+ * On AMD platforms BIOS advertises the bus clear feature
+ * and enables the SCL/SDA stuck low. SMU FW does the
+ * bus recovery process. Driver should not ignore this BIOS
+ * advertisement of bus clear feature.
+ */
+ ret = i2c_dw_acquire_lock(dev);
+ if (ret)
+ return ret;
+
+ ret = regmap_read(dev->map, DW_IC_CON, &ic_con);
+ i2c_dw_release_lock(dev);
+ if (ret)
+ return ret;
+
+ if (ic_con & DW_IC_CON_BUS_CLEAR_CTRL)
+ dev->master_cfg |= DW_IC_CON_BUS_CLEAR_CTRL;
+
ret = dev->init(dev);
if (ret)
return ret;
On some AMD platforms, based on the new designware datasheet, BIOS sets the BIT(11) within the IC_CON register to advertise the "bus clear feature capability". AMD/Designware datasheet says: Bit(11) BUS_CLEAR_FEATURE_CTRL. Read-write,Volatile. Reset: 0. Description: In Master mode: - 1'b1: Bus Clear Feature is enabled. - 1'b0: Bus Clear Feature is Disabled. In Slave mode, this register bit is not applicable. On AMD platform designs: 1. BIOS programs the BUS_CLEAR_FEATURE_CTRL and enables the detection of SCL/SDA stuck low. 2. Whenever the stuck low is detected, the SMU FW shall do the bus recovery procedure. Currently, the way in which the "master_cfg" is built in the driver, it overrides the BUS_CLEAR_FEATURE_CTRL advertised by BIOS and the SMU FW cannot initiate the bus recovery if the stuck low is detected. Hence add a check in i2c_dw_probe_master() that if the BIOS advertises the bus clear feature, let driver not ignore it and adapt accordingly. Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com> --- v2->v3: - Use regmap_read() instead of ioread32() - Move the proposed changes to i2c_dw_probe_master() and protect the regmap read calls with acquire/release lock calls. v1->v2: - Update the commit message drivers/i2c/busses/i2c-designware-core.h | 1 + drivers/i2c/busses/i2c-designware-master.c | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+)