diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/i2c/busses/i2c-rk3x.c | 55 |
1 files changed, 32 insertions, 23 deletions
diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c index 7e45d5101d32..1e2677ae1638 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 */ |