diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-exynos5.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-exynos5.c | 80 |
1 files changed, 75 insertions, 5 deletions
diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c index 2b0b9cdffa86..385ef9d9e4d4 100644 --- a/drivers/i2c/busses/i2c-exynos5.c +++ b/drivers/i2c/busses/i2c-exynos5.c @@ -194,6 +194,11 @@ struct exynos5_i2c { */ int trans_done; + /* + * Called from atomic context, don't use interrupts. + */ + unsigned int atomic; + /* Controller operating frequency */ unsigned int op_clock; @@ -265,7 +270,7 @@ static void exynos5_i2c_clr_pend_irq(struct exynos5_i2c *i2c) * exynos5_i2c_set_timing: updates the registers with appropriate * timing values calculated * - * Timing values for operation are calculated against either 100kHz + * Timing values for operation are calculated against 100kHz, 400kHz * or 1MHz controller operating frequency. * * Returns 0 on success, -EINVAL if the cycle length cannot @@ -328,6 +333,23 @@ static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c, bool hs_timings) * * Constraints: 4 <= temp, 0 <= CLK_DIV < 256, 2 <= clk_cycle <= 510 * + * To split SCL clock into low, high periods appropriately, one + * proportion factor for each I2C mode is used, which is calculated + * using this formula. + * ``` + * ((t_low_min + (scl_clock - t_low_min - t_high_min) / 2) / scl_clock) + * ``` + * where: + * t_low_min is the minimal value of low period of the SCL clock in us; + * t_high_min is the minimal value of high period of the SCL clock in us; + * scl_clock is converted from SCL clock frequency into us. + * + * Below are the proportion factors for these I2C modes: + * t_low_min, t_high_min, scl_clock, proportion + * Standard Mode: 4.7us, 4.0us, 10us, 0.535 + * Fast Mode: 1.3us, 0.6us, 2.5us, 0.64 + * Fast-Plus Mode: 0.5us, 0.26us, 1us, 0.62 + * */ t_ftl_cycle = (readl(i2c->regs + HSI2C_CONF) >> 16) & 0x7; temp = clkin / op_clk - 8 - t_ftl_cycle; @@ -341,8 +363,19 @@ static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c, bool hs_timings) return -EINVAL; } - t_scl_l = clk_cycle / 2; - t_scl_h = clk_cycle / 2; + /* + * Scale clk_cycle to get t_scl_l using the proption factors for individual I2C modes. + */ + if (op_clk <= I2C_MAX_STANDARD_MODE_FREQ) + t_scl_l = clk_cycle * 535 / 1000; + else if (op_clk <= I2C_MAX_FAST_MODE_FREQ) + t_scl_l = clk_cycle * 64 / 100; + else + t_scl_l = clk_cycle * 62 / 100; + + if (t_scl_l > 0xFF) + t_scl_l = 0xFF; + t_scl_h = clk_cycle - t_scl_l; t_start_su = t_scl_l; t_start_hd = t_scl_l; t_stop_su = t_scl_l; @@ -711,6 +744,22 @@ static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop) spin_unlock_irqrestore(&i2c->lock, flags); } +static bool exynos5_i2c_poll_irqs_timeout(struct exynos5_i2c *i2c, + unsigned long timeout) +{ + unsigned long time_left = jiffies + timeout; + + while (time_before(jiffies, time_left) && + !((i2c->trans_done && (i2c->msg->len == i2c->msg_ptr)) || + (i2c->state < 0))) { + while (readl(i2c->regs + HSI2C_INT_ENABLE) & + readl(i2c->regs + HSI2C_INT_STATUS)) + exynos5_i2c_irq(i2c->irq, i2c); + usleep_range(100, 200); + } + return time_before(jiffies, time_left); +} + static int exynos5_i2c_xfer_msg(struct exynos5_i2c *i2c, struct i2c_msg *msgs, int stop) { @@ -725,8 +774,13 @@ static int exynos5_i2c_xfer_msg(struct exynos5_i2c *i2c, exynos5_i2c_message_start(i2c, stop); - timeout = wait_for_completion_timeout(&i2c->msg_complete, - EXYNOS5_I2C_TIMEOUT); + if (!i2c->atomic) + timeout = wait_for_completion_timeout(&i2c->msg_complete, + EXYNOS5_I2C_TIMEOUT); + else + timeout = exynos5_i2c_poll_irqs_timeout(i2c, + EXYNOS5_I2C_TIMEOUT); + if (timeout == 0) ret = -ETIMEDOUT; else @@ -777,6 +831,21 @@ err_pclk: return ret ?: num; } +static int exynos5_i2c_xfer_atomic(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + struct exynos5_i2c *i2c = adap->algo_data; + int ret; + + disable_irq(i2c->irq); + i2c->atomic = true; + ret = exynos5_i2c_xfer(adap, msgs, num); + i2c->atomic = false; + enable_irq(i2c->irq); + + return ret; +} + static u32 exynos5_i2c_func(struct i2c_adapter *adap) { return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK); @@ -784,6 +853,7 @@ static u32 exynos5_i2c_func(struct i2c_adapter *adap) static const struct i2c_algorithm exynos5_i2c_algorithm = { .master_xfer = exynos5_i2c_xfer, + .master_xfer_atomic = exynos5_i2c_xfer_atomic, .functionality = exynos5_i2c_func, }; |