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i2c: sh_mobile: add helper to check frequency calculations 

Because we will add a second formula soon, put the sanity checks for the
computed results into a separate function.

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 22:58:00 +01:00 committed by Wolfram Sang
parent 023c22fd82
commit c3449f73a8
1 changed files with 29 additions and 24 deletions
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53
drivers/i2c/busses/i2c-sh_mobile.c
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@ -246,32 +246,10 @@ static u32 sh_mobile_i2c_icch(unsigned long count_khz, u32 tHIGH, u32 tf)
return (((count_khz * (tHIGH + tf)) + 5000) / 10000);
}
static int sh_mobile_i2c_init(struct sh_mobile_i2c_data *pd)
static int sh_mobile_i2c_check_timing(struct sh_mobile_i2c_data *pd)
{
unsigned long i2c_clk_khz;
u32 tHIGH, tLOW, tf;
uint16_t max_val;
u16 max_val = pd->flags & IIC_FLAG_HAS_ICIC67 ? 0x1ff : 0xff;
i2c_clk_khz = clk_get_rate(pd->clk) / 1000 / pd->clks_per_count;
if (pd->bus_speed == STANDARD_MODE) {
tLOW = 47; /* tLOW = 4.7 us */
tHIGH = 40; /* tHD;STA = tHIGH = 4.0 us */
tf = 3; /* tf = 0.3 us */
} else if (pd->bus_speed == FAST_MODE) {
tLOW = 13; /* tLOW = 1.3 us */
tHIGH = 6; /* tHD;STA = tHIGH = 0.6 us */
tf = 3; /* tf = 0.3 us */
} else {
dev_err(pd->dev, "unrecognized bus speed %lu Hz\n",
pd->bus_speed);
return -EINVAL;
}
pd->iccl = sh_mobile_i2c_iccl(i2c_clk_khz, tLOW, tf);
pd->icch = sh_mobile_i2c_icch(i2c_clk_khz, tHIGH, tf);
max_val = pd->flags & IIC_FLAG_HAS_ICIC67 ? 0x1ff : 0xff;
if (pd->iccl > max_val || pd->icch > max_val) {
dev_err(pd->dev, "timing values out of range: L/H=0x%x/0x%x\n",
pd->iccl, pd->icch);
@ -294,6 +272,33 @@ static int sh_mobile_i2c_init(struct sh_mobile_i2c_data *pd)
return 0;
}
static int sh_mobile_i2c_init(struct sh_mobile_i2c_data *pd)
{
unsigned long i2c_clk_khz;
u32 tHIGH, tLOW, tf;
i2c_clk_khz = clk_get_rate(pd->clk) / 1000 / pd->clks_per_count;
if (pd->bus_speed == STANDARD_MODE) {
tLOW = 47; /* tLOW = 4.7 us */
tHIGH = 40; /* tHD;STA = tHIGH = 4.0 us */
tf = 3; /* tf = 0.3 us */
} else if (pd->bus_speed == FAST_MODE) {
tLOW = 13; /* tLOW = 1.3 us */
tHIGH = 6; /* tHD;STA = tHIGH = 0.6 us */
tf = 3; /* tf = 0.3 us */
} else {
dev_err(pd->dev, "unrecognized bus speed %lu Hz\n",
pd->bus_speed);
return -EINVAL;
}
pd->iccl = sh_mobile_i2c_iccl(i2c_clk_khz, tLOW, tf);
pd->icch = sh_mobile_i2c_icch(i2c_clk_khz, tHIGH, tf);
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)
{