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Date: Mon, 15 Aug 2016 15:31:32 -0700
From: Stephen Boyd <sboyd@...eaurora.org>
To: Abhishek Sahu <absahu@...eaurora.org>
Cc: andy.gross@...aro.org, david.brown@...aro.org, robh+dt@...nel.org,
pawel.moll@....com, mark.rutland@....com,
ijc+devicetree@...lion.org.uk, mturquette@...libre.com,
galak@...eaurora.org, pradeepb@...eaurora.org,
mmcclint@...eaurora.org, varada@...eaurora.org,
sricharan@...eaurora.org, architt@...eaurora.org,
ntelkar@...eaurora.org, linux-arm-msm@...r.kernel.org,
linux-soc@...r.kernel.org, linux-clk@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/5] clk: qcom: ipq4019: Added the apss cpu pll
divider clock node
On 06/21, Abhishek Sahu wrote:
> diff --git a/drivers/clk/qcom/gcc-ipq4019.c b/drivers/clk/qcom/gcc-ipq4019.c
> index 17ca6d3..4c8a97f 100644
> --- a/drivers/clk/qcom/gcc-ipq4019.c
> +++ b/drivers/clk/qcom/gcc-ipq4019.c
> @@ -154,7 +154,7 @@ static const char * const gcc_xo_ddr_500_200[] = {
> "xo",
> "gcc_fepll200_clk",
> "gcc_fepll500_clk",
> - "ddrpllapss",
> + "gcc_apps_cpu_plldiv_clk",
> };
>
> #define F(f, s, h, m, n) { (f), (s), (2 * (h) - 1), (m), (n) }
> @@ -571,6 +571,7 @@ static struct clk_rcg2 apps_clk_src = {
> .parent_names = gcc_xo_ddr_500_200,
> .num_parents = 4,
> .ops = &clk_rcg2_ops,
> + .flags = CLK_SET_RATE_PARENT,
> },
> };
>
> @@ -1273,6 +1274,114 @@ static struct clk_pll_vco gcc_fepll_vco = {
> },
> };
>
> +/*
> + * Round rate function for APPS CPU PLL Clock divider.
> + * It Returns the input rate without changing it. The hardware supported rate
> + * will be calculated in set function by getting the same from frequency table.
> + */
> +static long clk_cpu_div_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *p_rate)
> +{
> + return rate;
This needs to calculate what the rate will be if clk_set_rate()
is called with the rate parameter. Blindly returning rate back is not
acceptable.
> +};
> +
> +/*
> + * Clock set rate function for APPS CPU PLL Clock divider.
> + * It looks up the frequency table and updates the PLL divider to corresponding
> + * divider value.
> + */
> +static int clk_cpu_div_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct clk_pll_div *rcg = to_clk_pll_div(hw);
> + const struct freq_tbl *f;
> + u32 mask;
> + int ret;
> +
> + f = qcom_find_freq(rcg->freq_tbl, rate);
> + if (!f)
> + return -EINVAL;
> +
> + mask = (BIT(rcg->cdiv.width) - 1) << rcg->cdiv.shift;
> + ret = regmap_update_bits(rcg->cdiv.clkr.regmap,
> + rcg->cdiv.reg, mask,
> + (f->pre_div << rcg->cdiv.shift) & mask);
Why are we masking a value that will be masked by
regmap_update_bits()?
> + udelay(1);
Why do we wait? Please add some comment.
> +
> + return 0;
> +};
> +
> +/*
> + * Clock frequency calculation function for APPS CPU PLL Clock divider.
> + * This clock divider is nonlinear so this function calculates the actual
> + * divider and returns the output frequency by dividing VCO Frequency
> + * with this actual divider value.
> + */
> +static unsigned long clk_cpu_div_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct clk_pll_div *rcg = to_clk_pll_div(hw);
> + u32 cdiv, pre_div;
> +
> + regmap_read(rcg->cdiv.clkr.regmap, rcg->cdiv.reg, &cdiv);
> + cdiv = (cdiv >> rcg->cdiv.shift) & (BIT(rcg->cdiv.width) - 1);
> +
> + /*
> + * Some dividers have value in 0.5 fraction so multiply both VCO
> + * frequency(parent_rate) and pre_div with 2 to make integer
> + * calculation.
> + */
> + if (cdiv > 10)
> + pre_div = (cdiv + 1) * 2;
> + else
> + pre_div = cdiv + 12;
> +
> + return clk_calc_divider_rate(parent_rate * 2, pre_div);
> +};
> +
> +const struct clk_ops clk_regmap_cpu_div_ops = {
static?
> + .round_rate = clk_cpu_div_round_rate,
> + .set_rate = clk_cpu_div_set_rate,
> + .recalc_rate = clk_cpu_div_recalc_rate,
> +};
> +
> +static const struct freq_tbl ftbl_apps_ddr_pll[] = {
> + {380000000, P_XO, 0xD, 0},
> + {409000000, P_XO, 0xC, 0, 0},
> + {444000000, P_XO, 0xB, 0, 0},
> + {484000000, P_XO, 0xA, 0, 0},
> + {507000000, P_XO, 0x9, 0, 0},
> + {532000000, P_XO, 0x8, 0, 0},
> + {560000000, P_XO, 0x7, 0, 0},
> + {592000000, P_XO, 0x6, 0, 0},
> + {626000000, P_XO, 0x5, 0, 0},
> + {666000000, P_XO, 0x4, 0, 0},
> + {710000000, P_XO, 0x3, 0, 0},
> + {761000000, P_XO, 0x2, 0, 0},
> + {819000000, P_XO, 0x1, 0, 0},
> + {888000000, P_XO, 0x0, 0, 0},
Style nits from before apply here (lowercase, spaces)
> + {}
> +};
> +
> +static struct clk_pll_div gcc_apps_cpu_plldiv_clk = {
> + .cdiv.reg = 0x2E020,
> + .cdiv.shift = 4,
> + .cdiv.width = 4,
> + .cdiv.clkr = {
> + .enable_reg = 0x2E000,
> + .enable_mask = BIT(0),
> + .hw.init = &(struct clk_init_data){
> + .name = "gcc_apps_cpu_plldiv_clk",
> + .parent_names = (const char *[]){
> + "gcc_apps_ddrpll_vco",
> + },
> + .num_parents = 1,
> + .ops = &clk_regmap_cpu_div_ops,
> + },
> + },
> + .freq_tbl = ftbl_apps_ddr_pll,
> +};
--
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