From: David Wu <david.wu@rock-chips.com>
To: heiko@sntech.de, wsa@the-dreams.de
Cc: robh+dt@kernel.org, dianders@chromium.org,
andy.shevchenko@gmail.com, pawel.moll@arm.com,
mark.rutland@arm.com, ijc+devicetree@hellion.org.uk,
galak@codeaurora.org, briannorris@google.com,
davidriley@google.com, huangtao@rock-chips.com,
hl@rock-chips.com, xjq@rock-chips.com, zyw@rock-chips.com,
cf@rock-chips.com, linux-arm-kernel@lists.infradead.org,
linux-rockchip@lists.infradead.org, linux-i2c@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
David Wu <david.wu@rock-chips.com>
Subject: [PATCH v10 2/8] i2c: rk3x: use struct "rk3x_i2c_calced_timings"
Date: Mon, 16 May 2016 21:57:37 +0800 [thread overview]
Message-ID: <1463407063-41218-3-git-send-email-david.wu@rock-chips.com> (raw)
In-Reply-To: <1463407063-41218-1-git-send-email-david.wu@rock-chips.com>
The "div_high" and "div_low" values are always used together.
Group them into a structure to make it easier to pass them
both around. This structure also provides a place for future
calculated timings.
Signed-off-by: David Wu <david.wu@rock-chips.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
---
Change in v10:
- none
Change in v9:
- none
Change in v8:
- add commit description.
drivers/i2c/busses/i2c-rk3x.c | 55 +++++++++++++++++++++++++------------------
1 file changed, 32 insertions(+), 23 deletions(-)
diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
index 7e45d51..1e2677a 100644
--- a/drivers/i2c/busses/i2c-rk3x.c
+++ b/drivers/i2c/busses/i2c-rk3x.c
@@ -75,6 +75,16 @@ enum {
#define WAIT_TIMEOUT 1000 /* ms */
#define DEFAULT_SCL_RATE (100 * 1000) /* Hz */
+/**
+ * struct rk3x_i2c_calced_timings:
+ * @div_low: Divider output for low
+ * @div_high: Divider output for high
+ */
+struct rk3x_i2c_calced_timings {
+ unsigned long div_low;
+ unsigned long div_high;
+};
+
enum rk3x_i2c_state {
STATE_IDLE,
STATE_START,
@@ -454,9 +464,8 @@ out:
* Calculate divider values for desired SCL frequency
*
* @clk_rate: I2C input clock rate
- * @t: Known I2C timing information.
- * @div_low: Divider output for low
- * @div_high: Divider output for high
+ * @t: Known I2C timing information
+ * @t_calc: Caculated rk3x private timings that would be written into regs
*
* Returns: 0 on success, -EINVAL if the goal SCL rate is too slow. In that case
* a best-effort divider value is returned in divs. If the target rate is
@@ -464,8 +473,7 @@ out:
*/
static int rk3x_i2c_calc_divs(unsigned long clk_rate,
struct i2c_timings *t,
- unsigned long *div_low,
- unsigned long *div_high)
+ struct rk3x_i2c_calced_timings *t_calc)
{
unsigned long spec_min_low_ns, spec_min_high_ns;
unsigned long spec_setup_start, spec_max_data_hold_ns;
@@ -572,8 +580,8 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate,
* Time needed to meet hold requirements is important.
* Just use that.
*/
- *div_low = min_low_div;
- *div_high = min_high_div;
+ t_calc->div_low = min_low_div;
+ t_calc->div_high = min_high_div;
} else {
/*
* We've got to distribute some time among the low and high
@@ -602,25 +610,25 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate,
/* Give low the "ideal" and give high whatever extra is left */
extra_low_div = ideal_low_div - min_low_div;
- *div_low = ideal_low_div;
- *div_high = min_high_div + (extra_div - extra_low_div);
+ t_calc->div_low = ideal_low_div;
+ t_calc->div_high = min_high_div + (extra_div - extra_low_div);
}
/*
* Adjust to the fact that the hardware has an implicit "+1".
* NOTE: Above calculations always produce div_low > 0 and div_high > 0.
*/
- *div_low = *div_low - 1;
- *div_high = *div_high - 1;
+ t_calc->div_low--;
+ t_calc->div_high--;
/* Maximum divider supported by hw is 0xffff */
- if (*div_low > 0xffff) {
- *div_low = 0xffff;
+ if (t_calc->div_low > 0xffff) {
+ t_calc->div_low = 0xffff;
ret = -EINVAL;
}
- if (*div_high > 0xffff) {
- *div_high = 0xffff;
+ if (t_calc->div_high > 0xffff) {
+ t_calc->div_high = 0xffff;
ret = -EINVAL;
}
@@ -630,19 +638,21 @@ static int rk3x_i2c_calc_divs(unsigned long clk_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;
+ struct rk3x_i2c_calced_timings calc;
u64 t_low_ns, t_high_ns;
int ret;
- ret = rk3x_i2c_calc_divs(clk_rate, t, &div_low, &div_high);
+ ret = rk3x_i2c_calc_divs(clk_rate, t, &calc);
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);
+ i2c_writel(i2c, (calc.div_high << 16) | (calc.div_low & 0xffff),
+ REG_CLKDIV);
clk_disable(i2c->clk);
- t_low_ns = div_u64(((u64)div_low + 1) * 8 * 1000000000, clk_rate);
- t_high_ns = div_u64(((u64)div_high + 1) * 8 * 1000000000, clk_rate);
+ t_low_ns = div_u64(((u64)calc.div_low + 1) * 8 * 1000000000, clk_rate);
+ t_high_ns = div_u64(((u64)calc.div_high + 1) * 8 * 1000000000,
+ clk_rate);
dev_dbg(i2c->dev,
"CLK %lukhz, Req %uns, Act low %lluns high %lluns\n",
clk_rate / 1000,
@@ -672,12 +682,11 @@ static int rk3x_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long
{
struct clk_notifier_data *ndata = data;
struct rk3x_i2c *i2c = container_of(nb, struct rk3x_i2c, clk_rate_nb);
- unsigned long div_low, div_high;
+ struct rk3x_i2c_calced_timings calc;
switch (event) {
case PRE_RATE_CHANGE:
- if (rk3x_i2c_calc_divs(ndata->new_rate, &i2c->t,
- &div_low, &div_high) != 0)
+ if (rk3x_i2c_calc_divs(ndata->new_rate, &i2c->t, &calc) != 0)
return NOTIFY_STOP;
/* scale up */
--
1.9.1
next prev parent reply other threads:[~2016-05-16 14:14 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-16 13:57 [PATCH v10 0/8] add i2c driver supported for rk3399 David Wu
2016-05-16 13:57 ` [PATCH v10 1/8] i2c: rk3x: add documentation to fields in "struct rk3x_i2c" David Wu
2016-05-16 13:57 ` David Wu [this message]
2016-05-16 13:57 ` [PATCH v10 3/8] i2c: rk3x: Remove redundant rk3x_i2c_clean_ipd() David Wu
2016-05-16 13:57 ` [PATCH v10 4/8] i2c: rk3x: Change SoC data to not use array David Wu
2016-05-16 14:03 ` [PATCH v10 5/8] i2c: rk3x: Move spec timing data to "static const" structs David Wu
2016-05-16 14:04 ` [PATCH v10 6/8] dt-bindings: i2c: rk3x: add support for rk3399 David Wu
2016-05-16 16:45 ` Rob Herring
2016-05-16 14:05 ` [PATCH v10 7/8] i2c: rk3x: add i2c support for rk3399 soc David Wu
2016-05-16 17:22 ` Doug Anderson
2016-05-16 14:06 ` [PATCH v10 8/8] i2c: rk3x: support fast-mode plus for rk3399 David Wu
2016-05-16 20:17 ` [PATCH v10 0/8] add i2c driver supported " Doug Anderson
2016-06-08 15:47 ` Heiko Stübner
2016-06-09 7:47 ` Wolfram Sang
2016-06-09 14:12 ` Heiko Stübner
2016-06-17 11:56 ` Wolfram Sang
2016-06-20 2:18 ` David.Wu
2016-06-20 2:18 ` David.Wu
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