Re: [PATCH v9 3/5] clk: imx: add SCCG PLL type

[Stephen Boyd]

Quoting Abel Vesa (2018-09-24 03:39:55)
> diff --git a/drivers/clk/imx/clk-sccg-pll.c b/drivers/clk/imx/clk-sccg-pll.c
> new file mode 100644
> index 0000000..a9837fa
> --- /dev/null
> +++ b/drivers/clk/imx/clk-sccg-pll.c
> @@ -0,0 +1,237 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +/*
> + * Copyright 2018 NXP.
> + */
> +
> +#include <linux/clk.h>

Is this include used? Otherwise should see clk-provider.h included here.

> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/slab.h>
> +#include <linux/delay.h>
> +#include <linux/bitfield.h>
> +
> +#include "clk.h"
> +
> +/* PLL CFGs */
> +#define PLL_CFG0               0x0
> +#define PLL_CFG1               0x4
> +#define PLL_CFG2               0x8
> +
> +#define PLL_DIVF1_MASK         GENMASK(18, 13)
> +#define PLL_DIVF2_MASK         GENMASK(12, 7)
> +#define PLL_DIVR1_MASK         GENMASK(27, 25)
> +#define PLL_DIVR2_MASK         GENMASK(24, 19)
> +#define PLL_REF_MASK           GENMASK(2, 0)
> +
> +#define PLL_LOCK_MASK          BIT(31)
> +#define PLL_PD_MASK            BIT(7)
> +
> +#define OSC_25M                        25000000
> +#define OSC_27M                        27000000
> +
> +#define PLL_SCCG_LOCK_TIMEOUT  70
> +
> +struct clk_sccg_pll {
> +       struct clk_hw   hw;
> +       void __iomem    *base;
> +};
> +
> +#define to_clk_sccg_pll(_hw) container_of(_hw, struct clk_sccg_pll, hw)
> +
> +static int clk_pll_wait_lock(struct clk_sccg_pll *pll)
> +{
> +       u32 val;
> +
> +       return readl_poll_timeout(pll->base, val, val & PLL_LOCK_MASK, 0,
> +                                       PLL_SCCG_LOCK_TIMEOUT);
> +}
> +
> +static int clk_pll1_is_prepared(struct clk_hw *hw)
> +{
> +       struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> +       u32 val;
> +
> +       val = readl_relaxed(pll->base + PLL_CFG0);
> +       return (val & PLL_PD_MASK) ? 0 : 1;
> +}
> +
> +static unsigned long clk_pll1_recalc_rate(struct clk_hw *hw,
> +                                        unsigned long parent_rate)
> +{
> +       struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> +       u32 val, divf;
> +
> +       val = readl_relaxed(pll->base + PLL_CFG2);
> +       divf = FIELD_GET(PLL_DIVF1_MASK, val);
> +
> +       return parent_rate * 2 * (divf + 1);
> +}
> +
> +static long clk_pll1_round_rate(struct clk_hw *hw, unsigned long rate,
> +                              unsigned long *prate)
> +{
> +       unsigned long parent_rate = *prate;
> +       u32 div;
> +
> +       div = rate / (parent_rate * 2);

Can parent_rate be 0?

> +
> +       return parent_rate * div * 2;
> +}
> +
> +static int clk_pll1_set_rate(struct clk_hw *hw, unsigned long rate,
> +                           unsigned long parent_rate)
> +{
> +       struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> +       u32 val;
> +       u32 divf;
> +
> +       divf = rate / (parent_rate * 2);

Can parent_rate be 0?

> +
> +       val = readl_relaxed(pll->base + PLL_CFG2);
> +       val &= ~PLL_DIVF1_MASK;
> +       val |= FIELD_PREP(PLL_DIVF1_MASK, divf - 1);
> +       writel_relaxed(val, pll->base + PLL_CFG2);
> +
> +       return clk_pll_wait_lock(pll);
> +}
> +
> +static int clk_pll1_prepare(struct clk_hw *hw)
> +{
> +       struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> +       u32 val;
> +
> +       val = readl_relaxed(pll->base + PLL_CFG0);
> +       val &= ~PLL_PD_MASK;
> +       writel_relaxed(val, pll->base + PLL_CFG0);
> +
> +       return clk_pll_wait_lock(pll);
> +}
> +
> +static void clk_pll1_unprepare(struct clk_hw *hw)
> +{
> +       struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> +       u32 val;
> +
> +       val = readl_relaxed(pll->base + PLL_CFG0);
> +       val |= PLL_PD_MASK;
> +       writel_relaxed(val, pll->base + PLL_CFG0);
> +
> +}
> +
> +static unsigned long clk_pll2_recalc_rate(struct clk_hw *hw,
> +                                        unsigned long parent_rate)
> +{
> +       struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> +       u32 val, ref, divr1, divf1, divr2, divf2;
> +       u64 temp64;
> +
> +       val = readl_relaxed(pll->base + PLL_CFG0);
> +       switch (FIELD_GET(PLL_REF_MASK, val)) {
> +       case 0:
> +               ref = OSC_25M;
> +               break;
> +       case 1:
> +               ref = OSC_27M;
> +               break;
> +       default:
> +               ref = OSC_25M;

Does this information not come through 'parent_rate'?

> +               break;
> +       }
> +
> +       val = readl_relaxed(pll->base + PLL_CFG2);
> +       divr1 = FIELD_GET(PLL_DIVR1_MASK, val);
> +       divr2 = FIELD_GET(PLL_DIVR2_MASK, val);
> +       divf1 = FIELD_GET(PLL_DIVF1_MASK, val);
> +       divf2 = FIELD_GET(PLL_DIVF2_MASK, val);
> +
> +       temp64 = ref * 2;
> +       temp64 *= (divf1 + 1) * (divf2 + 1);
> +
> +       do_div(temp64, (divr1 + 1) * (divr2 + 1));

Nitpicks: A comment with the equation may be helpful to newcomers.

> +
> +       return (unsigned long)temp64;

Drop useless cast please.

> +}
> +
> +static long clk_pll2_round_rate(struct clk_hw *hw, unsigned long rate,
> +                              unsigned long *prate)
> +{
> +       u32 div;
> +       unsigned long parent_rate = *prate;
> +
> +       div = rate / (parent_rate);
> +
> +       return parent_rate * div;
> +}
> +
> +static int clk_pll2_set_rate(struct clk_hw *hw, unsigned long rate,
> +                           unsigned long parent_rate)
> +{
> +       u32 val;
> +       u32 divf;
> +       struct clk_sccg_pll *pll = to_clk_sccg_pll(hw);
> +
> +       divf = rate / (parent_rate);

Drop useless parenthesis please.

> +
> +       val = readl_relaxed(pll->base + PLL_CFG2);
> +       val &= ~PLL_DIVF2_MASK;
> +       val |= FIELD_PREP(PLL_DIVF2_MASK, divf - 1);
> +       writel_relaxed(val, pll->base + PLL_CFG2);
> +
> +       return clk_pll_wait_lock(pll);
> +}
> +
> +static const struct clk_ops clk_sccg_pll1_ops = {
> +       .is_prepared    = clk_pll1_is_prepared,
> +       .recalc_rate    = clk_pll1_recalc_rate,
> +       .round_rate     = clk_pll1_round_rate,
> +       .set_rate       = clk_pll1_set_rate,
> +};
> +
> +static const struct clk_ops clk_sccg_pll2_ops = {
> +       .prepare        = clk_pll1_prepare,
> +       .unprepare      = clk_pll1_unprepare,
> +       .recalc_rate    = clk_pll2_recalc_rate,
> +       .round_rate     = clk_pll2_round_rate,
> +       .set_rate       = clk_pll2_set_rate,
> +};
> +
> +struct clk *imx_clk_sccg_pll(const char *name,
> +                               const char *parent_name,
> +                               void __iomem *base,
> +                               enum imx_sccg_pll_type pll_type)
> +{
> +       struct clk_sccg_pll *pll;
> +       struct clk *clk;
> +       struct clk_init_data init;
> +
> +       pll = kzalloc(sizeof(*pll), GFP_KERNEL);
> +       if (!pll)
> +               return ERR_PTR(-ENOMEM);
> +
> +       pll->base = base;
> +       init.name = name;
> +       switch (pll_type) {
> +       case SCCG_PLL1:
> +               init.ops = &clk_sccg_pll1_ops;
> +               break;
> +       case SCCG_PLL2:
> +               init.ops = &clk_sccg_pll2_ops;
> +               break;
> +       default:
> +               kfree(pll);
> +               return ERR_PTR(-EINVAL);

Do this case statement before allocating? So that kfree() isn't required
here?

> +       }
> +
> +       init.flags = 0;
> +       init.parent_names = &parent_name;
> +       init.num_parents = 1;
> +
> +       pll->hw.init = &init;
> +
> +       clk = clk_register(NULL, &pll->hw);

Any chance to use clk_hw based registration APIs?

> +       if (IS_ERR(clk))
> +               kfree(pll);
> +
> +       return clk;