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authorWolfram Sang <wsa+renesas@sang-engineering.com>2017-12-18 22:58:01 +0100
committerWolfram Sang <wsa@the-dreams.de>2018-01-15 18:01:14 +0100
commit4ecfb9d3b229fff538c706650a8208fa03660c22 (patch)
tree937577af66d9fd5f7b7db59e5862f825b436404a /drivers/i2c
parentc3449f73a80b2b04a3f7ff69be871c153ea1a9fa (diff)
i2c: sh_mobile: add new frequency calculation for later SoC
The formula to generate the desired bus speeds has changed a little over time. Implement the new formula and allow drivers to opt-in by changing to this new config set. Ensure in probe that we don't divide by zero. The returned values on a R-Car H2 (r8a7790/Lager board) match the suggested values in the datasheet. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-sh_mobile.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
index b111191a449a..a0fddfe3c449 100644
--- a/drivers/i2c/busses/i2c-sh_mobile.c
+++ b/drivers/i2c/busses/i2c-sh_mobile.c
@@ -299,6 +299,18 @@ static int sh_mobile_i2c_init(struct sh_mobile_i2c_data *pd)
return sh_mobile_i2c_check_timing(pd);
}
+static int sh_mobile_i2c_v2_init(struct sh_mobile_i2c_data *pd)
+{
+ unsigned long clks_per_cycle;
+
+ /* L = 5, H = 4, L + H = 9 */
+ clks_per_cycle = clk_get_rate(pd->clk) / pd->bus_speed;
+ pd->iccl = DIV_ROUND_UP(clks_per_cycle * 5 / 9 - 1, pd->clks_per_count);
+ pd->icch = DIV_ROUND_UP(clks_per_cycle * 4 / 9 - 5, pd->clks_per_count);
+
+ return sh_mobile_i2c_check_timing(pd);
+}
+
static unsigned char i2c_op(struct sh_mobile_i2c_data *pd,
enum sh_mobile_i2c_op op, unsigned char data)
{
@@ -785,6 +797,11 @@ static const struct sh_mobile_dt_config fast_clock_dt_config = {
.setup = sh_mobile_i2c_init,
};
+static const struct sh_mobile_dt_config v2_freq_calc_dt_config = {
+ .clks_per_count = 2,
+ .setup = sh_mobile_i2c_v2_init,
+};
+
static const struct sh_mobile_dt_config r8a7740_dt_config = {
.clks_per_count = 1,
.setup = sh_mobile_i2c_r8a7740_workaround,
@@ -875,7 +892,7 @@ static int sh_mobile_i2c_probe(struct platform_device *dev)
return PTR_ERR(pd->reg);
ret = of_property_read_u32(dev->dev.of_node, "clock-frequency", &bus_speed);
- pd->bus_speed = ret ? STANDARD_MODE : bus_speed;
+ pd->bus_speed = (ret || !bus_speed) ? STANDARD_MODE : bus_speed;
pd->clks_per_count = 1;
/* Newer variants come with two new bits in ICIC */

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