[PATCH v5 1/2] i2c: rk3x: switch to i2c generic dt parsing

David Wu
2016-03-16T16:57:17Z

Switch to the new generic functions: i2c_parse_fw_timings().

Signed-off-by: David Wu <david.wu@rock-chips.com>
---
drivers/i2c/busses/i2c-rk3x.c | 87 ++++++++++++-------------------------------
1 file changed, 24 insertions(+), 63 deletions(-)

diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
index 9096d17..c4b0d89 100644
--- a/drivers/i2c/busses/i2c-rk3x.c
+++ b/drivers/i2c/busses/i2c-rk3x.c
@@ -101,10 +101,7 @@ struct rk3x_i2c {
struct notifier_block clk_rate_nb;

/* Settings */
- unsigned int scl_frequency;
- unsigned int scl_rise_ns;
- unsigned int scl_fall_ns;
- unsigned int sda_fall_ns;
+ struct i2c_timings t;

/* Synchronization & notification */
spinlock_t lock;
@@ -437,10 +434,7 @@ out:
* Calculate divider values for desired SCL frequency
*
* @clk_rate: I2C input clock rate
- * @scl_rate: Desired SCL rate
- * @scl_rise_ns: How many ns it takes for SCL to rise.
- * @scl_fall_ns: How many ns it takes for SCL to fall.
- * @sda_fall_ns: How many ns it takes for SDA to fall.
+ * @t: Known I2C timing information.
* @div_low: Divider output for low
* @div_high: Divider output for high
*
@@ -448,11 +442,10 @@ out:
* a best-effort divider value is returned in divs. If the target rate is
* too high, we silently use the highest possible rate.
*/
-static int rk3x_i2c_calc_divs(unsigned long clk_rate, unsigned long scl_rate,
- unsigned long scl_rise_ns,
- unsigned long scl_fall_ns,
- unsigned long sda_fall_ns,
- unsigned long *div_low, unsigned long *div_high)
+static int rk3x_i2c_calc_divs(unsigned long clk_rate,
+ struct i2c_timings *t,
+ unsigned long *div_low,
+ unsigned long *div_high)
{
unsigned long spec_min_low_ns, spec_min_high_ns;
unsigned long spec_setup_start, spec_max_data_hold_ns;
@@ -472,12 +465,12 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate, unsigned long scl_rate,
int ret = 0;

/* Only support standard-mode and fast-mode */
- if (WARN_ON(scl_rate > 400000))
- scl_rate = 400000;
+ if (WARN_ON(t->bus_freq_hz > 400000))
+ t->bus_freq_hz = 400000;

/* prevent scl_rate_khz from becoming 0 */
- if (WARN_ON(scl_rate < 1000))
- scl_rate = 1000;
+ if (WARN_ON(t->bus_freq_hz < 1000))
+ t->bus_freq_hz = 1000;

/*
* min_low_ns: The minimum number of ns we need to hold low to
@@ -491,7 +484,7 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate, unsigned long scl_rate,
* This is because the i2c host on Rockchip holds the data line
* for half the low time.
*/
- if (scl_rate <= 100000) {
+ if (t->bus_freq_hz <= 100000) {
/* Standard-mode */
spec_min_low_ns = 4700;
spec_setup_start = 4700;
@@ -506,7 +499,7 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate, unsigned long scl_rate,
spec_max_data_hold_ns = 900;
data_hold_buffer_ns = 50;
}
- min_high_ns = scl_rise_ns + spec_min_high_ns;
+ min_high_ns = t->scl_rise_ns + spec_min_high_ns;

/*
* Timings for repeated start:
@@ -517,18 +510,18 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate, unsigned long scl_rate,
* we meet tSU;STA and tHD;STA times.
*/
min_high_ns = max(min_high_ns,
- DIV_ROUND_UP((scl_rise_ns + spec_setup_start) * 1000, 875));
+ DIV_ROUND_UP((t->scl_rise_ns + spec_setup_start) * 1000, 875));
min_high_ns = max(min_high_ns,
- DIV_ROUND_UP((scl_rise_ns + spec_setup_start +
- sda_fall_ns + spec_min_high_ns), 2));
+ DIV_ROUND_UP((t->scl_rise_ns + spec_setup_start +
+ t->sda_fall_ns + spec_min_high_ns), 2));

- min_low_ns = scl_fall_ns + spec_min_low_ns;
+ min_low_ns = t->scl_fall_ns + spec_min_low_ns;
max_low_ns = spec_max_data_hold_ns * 2 - data_hold_buffer_ns;
min_total_ns = min_low_ns + min_high_ns;

/* Adjust to avoid overflow */
clk_rate_khz = DIV_ROUND_UP(clk_rate, 1000);
- scl_rate_khz = scl_rate / 1000;
+ scl_rate_khz = t->bus_freq_hz / 1000;

/*
* We need the total div to be >= this number
@@ -616,14 +609,13 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate, unsigned long scl_rate,

static void rk3x_i2c_adapt_div(struct rk3x_i2c *i2c, unsigned long clk_rate)
{
+ struct i2c_timings *t = &i2c->t;
unsigned long div_low, div_high;
u64 t_low_ns, t_high_ns;
int ret;

- ret = rk3x_i2c_calc_divs(clk_rate, i2c->scl_frequency, i2c->scl_rise_ns,
- i2c->scl_fall_ns, i2c->sda_fall_ns,
- &div_low, &div_high);
- WARN_ONCE(ret != 0, "Could not reach SCL freq %u", i2c->scl_frequency);
+ ret = rk3x_i2c_calc_divs(clk_rate, t, &div_low, &div_high);
+ WARN_ONCE(ret != 0, "Could not reach SCL freq %u", t->bus_freq_hz);

clk_enable(i2c->clk);
i2c_writel(i2c, (div_high << 16) | (div_low & 0xffff), REG_CLKDIV);
@@ -634,7 +626,7 @@ static void rk3x_i2c_adapt_div(struct rk3x_i2c *i2c, unsigned long clk_rate)
dev_dbg(i2c->dev,
"CLK %lukhz, Req %uns, Act low %lluns high %lluns\n",
clk_rate / 1000,
- 1000000000 / i2c->scl_frequency,
+ 1000000000 / t->bus_freq_hz,
t_low_ns, t_high_ns);
}

@@ -664,9 +656,7 @@ static int rk3x_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long

switch (event) {
case PRE_RATE_CHANGE:
- if (rk3x_i2c_calc_divs(ndata->new_rate, i2c->scl_frequency,
- i2c->scl_rise_ns, i2c->scl_fall_ns,
- i2c->sda_fall_ns,
+ if (rk3x_i2c_calc_divs(ndata->new_rate, &i2c->t,
&div_low, &div_high) != 0)
return NOTIFY_STOP;

@@ -879,37 +869,8 @@ static int rk3x_i2c_probe(struct platform_device *pdev)
match = of_match_node(rk3x_i2c_match, np);
i2c->soc_data = (struct rk3x_i2c_soc_data *)match->data;

- if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
- &i2c->scl_frequency)) {
- dev_info(&pdev->dev, "using default SCL frequency: %d\n",
- DEFAULT_SCL_RATE);
- i2c->scl_frequency = DEFAULT_SCL_RATE;
- }
-
- if (i2c->scl_frequency == 0 || i2c->scl_frequency > 400 * 1000) {
- dev_warn(&pdev->dev, "invalid SCL frequency specified.\n");
- dev_warn(&pdev->dev, "using default SCL frequency: %d\n",
- DEFAULT_SCL_RATE);
- i2c->scl_frequency = DEFAULT_SCL_RATE;
- }
-
- /*
- * Read rise and fall time from device tree. If not available use
- * the default maximum timing from the specification.
- */
- if (of_property_read_u32(pdev->dev.of_node, "i2c-scl-rising-time-ns",
- &i2c->scl_rise_ns)) {
- if (i2c->scl_frequency <= 100000)
- i2c->scl_rise_ns = 1000;
- else
- i2c->scl_rise_ns = 300;
- }
- if (of_property_read_u32(pdev->dev.of_node, "i2c-scl-falling-time-ns",
- &i2c->scl_fall_ns))
- i2c->scl_fall_ns = 300;
- if (of_property_read_u32(pdev->dev.of_node, "i2c-sda-falling-time-ns",
- &i2c->sda_fall_ns))
- i2c->sda_fall_ns = i2c->scl_fall_ns;
+ /* use common interface to get I2C timing properties */
+ i2c_parse_fw_timings(&pdev->dev, &i2c->t, true);

strlcpy(i2c->adap.name, "rk3x-i2c", sizeof(i2c->adap.name));
i2c->adap.owner = THIS_MODULE;
--
1.9.1