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SubjectRe: [PATCH v2 1/3] clk: qcom: clk-alpha-pll: Add support for controlling Agera PLLs
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Quoting Taniya Das (2020-10-13 10:11:48)
> diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
> index 26139ef..17e1fc0 100644
> --- a/drivers/clk/qcom/clk-alpha-pll.c
> +++ b/drivers/clk/qcom/clk-alpha-pll.c
> @@ -1561,3 +1571,73 @@ const struct clk_ops clk_alpha_pll_postdiv_lucid_ops = {
> .set_rate = clk_alpha_pll_postdiv_fabia_set_rate,
> };
> EXPORT_SYMBOL_GPL(clk_alpha_pll_postdiv_lucid_ops);
> +
> +void clk_agera_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
> + const struct alpha_pll_config *config)
> +{
> + if (config->l)
> + regmap_write(regmap, PLL_L_VAL(pll), config->l);

Maybe make a helper function for this too. That way we can't mix up the
if condition with the value in the write.

clk_alpha_pll_write_config(regmap, PLL_L_VAL(pll), config->l);

static void clk_alpha_pll_write_config(struct regmap *regmap,
unsigned int reg,
unsigned int val) {
if (val)
regmap_write(regmap, reg, val);
}

and how are we so lucky that zero isn't a value that we may need to
write?

> +
> + if (config->alpha)
> + regmap_write(regmap, PLL_ALPHA_VAL(pll), config->alpha);
> +
> + if (config->user_ctl_val)
> + regmap_write(regmap, PLL_USER_CTL(pll), config->user_ctl_val);
> +
> + if (config->config_ctl_val)
> + regmap_write(regmap, PLL_CONFIG_CTL(pll),
> + config->config_ctl_val);
> +
> + if (config->config_ctl_hi_val)
> + regmap_write(regmap, PLL_CONFIG_CTL_U(pll),
> + config->config_ctl_hi_val);
> +
> + if (config->test_ctl_val)
> + regmap_write(regmap, PLL_TEST_CTL(pll),
> + config->test_ctl_val);
> +
> + if (config->test_ctl_hi_val)
> + regmap_write(regmap, PLL_TEST_CTL_U(pll),
> + config->test_ctl_hi_val);
> +}
> +EXPORT_SYMBOL_GPL(clk_agera_pll_configure);
> +
> +static int clk_alpha_pll_agera_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long prate)
> +{
> + struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
> + u32 l, alpha_width = pll_alpha_width(pll);
> + unsigned long rrate, max = rate + PLL_RATE_MARGIN;
> + u64 a;
> +
> + rrate = alpha_pll_round_rate(rate, prate, &l, &a, alpha_width);
> +
> + /*
> + * Due to limited number of bits for fractional rate programming, the
> + * rounded up rate could be marginally higher than the requested rate.
> + */
> + if (rrate > (rate + PLL_RATE_MARGIN) || rrate < rate) {
> + pr_err("%s: Rounded rate %lu not within range [%lu, %lu)\n",
> + clk_hw_get_name(hw), rrate, rate, max);
> + return -EINVAL;
> + }

Can this be extracted into a helper function?

> +
> + /* change L_VAL without having to go through the power on sequence */
> + regmap_write(pll->clkr.regmap, PLL_L_VAL(pll), l);
> + regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), a);
> +
> + if (clk_hw_is_enabled(hw))
> + return wait_for_pll_enable_lock(pll);
> +
> + return 0;
> +}
> +

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