[PATCH i2c-next 2/2] i2c: aspeed: add slave inactive timeout support

Jae Hyun Yoo
2019-10-21T20:24:14Z

In case of multi-master environment, if a peer master incorrectly handles
a bus in the middle of a transaction, I2C hardware hangs in slave state
and it can't escape from the slave state, so this commit adds slave
inactive timeout support to recover the bus in the case.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Tao Ren <taoren@fb.com>
---
drivers/i2c/busses/i2c-aspeed.c | 83 ++++++++++++++++++++++++++++++---
1 file changed, 77 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index a7be6f24450b..d43687cd2ddc 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -7,6 +7,7 @@
* Copyright 2017 Google, Inc.
*/

+#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/err.h>
@@ -43,6 +44,7 @@

/* Device Register Definition */
/* 0x00 : I2CD Function Control Register */
+#define ASPEED_I2CD_BUS_AUTO_RECOVERY_EN BIT(17)
#define ASPEED_I2CD_MULTI_MASTER_DIS BIT(15)
#define ASPEED_I2CD_SDA_DRIVE_1T_EN BIT(8)
#define ASPEED_I2CD_M_SDA_DRIVE_1T_EN BIT(7)
@@ -58,10 +60,14 @@
#define ASPEED_I2CD_TIME_SCL_HIGH_MASK GENMASK(19, 16)
#define ASPEED_I2CD_TIME_SCL_LOW_SHIFT 12
#define ASPEED_I2CD_TIME_SCL_LOW_MASK GENMASK(15, 12)
+#define ASPEED_I2CD_TIME_TIMEOUT_BASE_DIVISOR_SHIFT 8
+#define ASPEED_I2CD_TIME_TIMEOUT_BASE_DIVISOR_MASK GENMASK(9, 8)
#define ASPEED_I2CD_TIME_BASE_DIVISOR_MASK GENMASK(3, 0)
#define ASPEED_I2CD_TIME_SCL_REG_MAX GENMASK(3, 0)
+
/* 0x08 : I2CD Clock and AC Timing Control Register #2 */
-#define ASPEED_NO_TIMEOUT_CTRL 0
+#define ASPEED_I2CD_TIMEOUT_CYCLES_SHIFT 0
+#define ASPEED_I2CD_TIMEOUT_CYCLES_MASK GENMASK(4, 0)

/* 0x0c : I2CD Interrupt Control Register &
* 0x10 : I2CD Interrupt Status Register
@@ -69,6 +75,7 @@
* These share bit definitions, so use the same values for the enable &
* status bits.
*/
+#define ASPEED_I2CD_INTR_SLAVE_INACTIVE_TIMEOUT BIT(15)
#define ASPEED_I2CD_INTR_SDA_DL_TIMEOUT BIT(14)
#define ASPEED_I2CD_INTR_BUS_RECOVER_DONE BIT(13)
#define ASPEED_I2CD_INTR_SLAVE_MATCH BIT(7)
@@ -84,8 +91,11 @@
ASPEED_I2CD_INTR_SCL_TIMEOUT | \
ASPEED_I2CD_INTR_ABNORMAL | \
ASPEED_I2CD_INTR_ARBIT_LOSS)
+#define ASPEED_I2CD_INTR_SLAVE_ERRORS \
+ ASPEED_I2CD_INTR_SLAVE_INACTIVE_TIMEOUT
#define ASPEED_I2CD_INTR_ALL \
- (ASPEED_I2CD_INTR_SDA_DL_TIMEOUT | \
+ (ASPEED_I2CD_INTR_SLAVE_INACTIVE_TIMEOUT | \
+ ASPEED_I2CD_INTR_SDA_DL_TIMEOUT | \
ASPEED_I2CD_INTR_BUS_RECOVER_DONE | \
ASPEED_I2CD_INTR_SCL_TIMEOUT | \
ASPEED_I2CD_INTR_ABNORMAL | \
@@ -151,6 +161,7 @@ struct aspeed_i2c_bus {
u32 divisor);
unsigned long parent_clk_frequency;
u32 bus_frequency;
+ u32 hw_timeout_ms;
/* Transaction state. */
enum aspeed_i2c_master_state master_state;
struct i2c_msg *msgs;
@@ -240,6 +251,14 @@ static int aspeed_i2c_recover_bus(struct aspeed_i2c_bus *bus)
}

#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static int aspeed_i2c_check_slave_error(u32 irq_status)
+{
+ if (irq_status & ASPEED_I2CD_INTR_SLAVE_INACTIVE_TIMEOUT)
+ return -EIO;
+
+ return 0;
+}
+
static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
{
u32 command, irq_handled = 0;
@@ -249,6 +268,14 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
if (!slave)
return 0;

+ if (aspeed_i2c_check_slave_error(irq_status)) {
+ dev_dbg(bus->dev, "received slave error interrupt: 0x%08x\n",
+ irq_status);
+ irq_handled |= (irq_status & ASPEED_I2CD_INTR_SLAVE_ERRORS);
+ bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
+ return irq_handled;
+ }
+
command = readl(bus->base + ASPEED_I2C_CMD_REG);

/* Slave was requested, restart state machine. */
@@ -386,7 +413,7 @@ static void aspeed_i2c_next_msg_or_stop(struct aspeed_i2c_bus *bus)
}
}

-static int aspeed_i2c_is_irq_error(u32 irq_status)
+static int aspeed_i2c_check_master_error(u32 irq_status)
{
if (irq_status & ASPEED_I2CD_INTR_ARBIT_LOSS)
return -EAGAIN;
@@ -417,9 +444,9 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
* should clear the command queue effectively taking us back to the
* INACTIVE state.
*/
- ret = aspeed_i2c_is_irq_error(irq_status);
+ ret = aspeed_i2c_check_master_error(irq_status);
if (ret) {
- dev_dbg(bus->dev, "received error interrupt: 0x%08x\n",
+ dev_dbg(bus->dev, "received master error interrupt: 0x%08x\n",
irq_status);
irq_handled |= (irq_status & ASPEED_I2CD_INTR_MASTER_ERRORS);
if (bus->master_state != ASPEED_I2C_MASTER_INACTIVE) {
@@ -875,6 +902,7 @@ static u32 aspeed_i2c_25xx_get_clk_reg_val(struct device *dev, u32 divisor)
/* precondition: bus.lock has been acquired. */
static int aspeed_i2c_init_clk(struct aspeed_i2c_bus *bus)
{
+ u32 timeout_base_divisor, timeout_tick_us, timeout_cycles;
u32 divisor, clk_reg_val;

divisor = DIV_ROUND_UP(bus->parent_clk_frequency, bus->bus_frequency);
@@ -883,8 +911,46 @@ static int aspeed_i2c_init_clk(struct aspeed_i2c_bus *bus)
ASPEED_I2CD_TIME_THDSTA_MASK |
ASPEED_I2CD_TIME_TACST_MASK);
clk_reg_val |= bus->get_clk_reg_val(bus->dev, divisor);
+
+ if (bus->hw_timeout_ms) {
+ u8 div_max = ASPEED_I2CD_TIME_TIMEOUT_BASE_DIVISOR_MASK >>
+ ASPEED_I2CD_TIME_TIMEOUT_BASE_DIVISOR_SHIFT;
+ u8 cycles_max = ASPEED_I2CD_TIMEOUT_CYCLES_MASK >>
+ ASPEED_I2CD_TIMEOUT_CYCLES_SHIFT;
+
+ timeout_base_divisor = 0;
+
+ do {
+ timeout_tick_us = 1000 * (16384 <<
+ (timeout_base_divisor << 1)) /
+ (bus->parent_clk_frequency / 1000);
+
+ if (timeout_base_divisor == div_max ||
+ timeout_tick_us * ASPEED_I2CD_TIMEOUT_CYCLES_MASK >=
+ bus->hw_timeout_ms * 1000)
+ break;
+ } while (timeout_base_divisor++ < div_max);
+
+ if (timeout_tick_us) {
+ timeout_cycles = DIV_ROUND_UP(bus->hw_timeout_ms * 1000,
+ timeout_tick_us);
+ if (timeout_cycles == 0)
+ timeout_cycles = 1;
+ else if (timeout_cycles > cycles_max)
+ timeout_cycles = cycles_max;
+ } else {
+ timeout_cycles = 0;
+ }
+ } else {
+ timeout_base_divisor = 0;
+ timeout_cycles = 0;
+ }
+
+ clk_reg_val |= FIELD_PREP(ASPEED_I2CD_TIME_TIMEOUT_BASE_DIVISOR_MASK,
+ timeout_base_divisor);
+
writel(clk_reg_val, bus->base + ASPEED_I2C_AC_TIMING_REG1);
- writel(ASPEED_NO_TIMEOUT_CTRL, bus->base + ASPEED_I2C_AC_TIMING_REG2);
+ writel(timeout_cycles, bus->base + ASPEED_I2C_AC_TIMING_REG2);

return 0;
}
@@ -899,6 +965,11 @@ static int aspeed_i2c_init(struct aspeed_i2c_bus *bus,
/* Disable everything. */
writel(0, bus->base + ASPEED_I2C_FUN_CTRL_REG);

+ device_property_read_u32(&pdev->dev, "aspeed,hw-timeout-ms",
+ &bus->hw_timeout_ms);
+ if (bus->hw_timeout_ms)
+ fun_ctrl_reg |= ASPEED_I2CD_BUS_AUTO_RECOVERY_EN;
+
ret = aspeed_i2c_init_clk(bus);
if (ret < 0)
return ret;
--
2.23.0