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i2c: sh_mobile: add new frequency calculation for later SoC

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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>
This commit is contained in:
Wolfram Sang 2017-12-18 22:58:01 +01:00 committed by Wolfram Sang
parent c3449f73a8
commit 4ecfb9d3b2
1 changed files with 18 additions and 1 deletions
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19
drivers/i2c/busses/i2c-sh_mobile.c
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@ -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 */