diff options
| author | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2017-12-18 22:58:01 +0100 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2018-01-15 18:01:14 +0100 |
| commit | 4ecfb9d3b229fff538c706650a8208fa03660c22 (patch) | |
| tree | 937577af66d9fd5f7b7db59e5862f825b436404a /drivers/i2c/busses/i2c-sh_mobile.c | |
| parent | c3449f73a80b2b04a3f7ff69be871c153ea1a9fa (diff) | |
| download | lwn-4ecfb9d3b229fff538c706650a8208fa03660c22.tar.gz lwn-4ecfb9d3b229fff538c706650a8208fa03660c22.zip | |
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/busses/i2c-sh_mobile.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-sh_mobile.c | 19 |
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 */ |