Re: [PATCH v3 3/4] clk: loongson1: Re-implement the clock driver

[Stephen Boyd]

Quoting Keguang Zhang (2023-03-16 03:47:06)
> diff --git a/drivers/clk/clk-loongson1.c b/drivers/clk/clk-loongson1.c
> new file mode 100644
> index 000000000000..4fda55c67d8d
> --- /dev/null
> +++ b/drivers/clk/clk-loongson1.c
> @@ -0,0 +1,301 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Clock driver for Loongson-1 SoC
> + *
> + * Copyright (C) 2012-2023 Keguang Zhang <keguang.zhang@xxxxxxxxx>
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/of_address.h>
> +#include <linux/slab.h>

Need some more includes here, for container_of() and GENMASK(), readl(),
etc.

> +
> +#include <dt-bindings/clock/loongson,ls1x-clk.h>
> +
> +/* Loongson 1 Clock Register Definitions */
> +#define CLK_PLL_FREQ           0x0
> +#define CLK_PLL_DIV            0x4
> +
> +static DEFINE_SPINLOCK(ls1x_clk_div_lock);
> +

Needs include.

> +struct ls1x_clk_pll_data {
> +       u32 fixed;
> +       u8 shift;
> +       u8 int_shift;
> +       u8 int_width;
> +       u8 frac_shift;
> +       u8 frac_width;
> +};
> +
> +struct ls1x_clk_div_data {
> +       u8 shift;
> +       u8 width;
> +       unsigned long flags;
> +       const struct clk_div_table *table;
> +       u8 bypass_shift;
> +       u8 bypass_inv;
> +       spinlock_t *lock;       /* protect access to DIV registers */
> +};
> +
> +struct ls1x_clk {
> +       void __iomem *reg;
> +       unsigned int offset;
> +       struct clk_hw hw;
> +       void *data;
> +};
> +
> +#define to_ls1x_clk(_hw) container_of(_hw, struct ls1x_clk, hw)
> +
> +static inline unsigned long ls1x_pll_rate_part(unsigned int val,

return a u32?

> +                                              unsigned int shift,
> +                                              unsigned int width)
> +{
> +       return (val & GENMASK(shift + width, shift)) >> shift;
> +}
> +
> +static unsigned long ls1x_pll_recalc_rate(struct clk_hw *hw,
> +                                         unsigned long parent_rate)
> +{
> +       struct ls1x_clk *ls1x_clk = to_ls1x_clk(hw);
> +       const struct ls1x_clk_pll_data *d = ls1x_clk->data;
> +       u32 val, rate;
> +
> +       val = readl(ls1x_clk->reg);
> +       rate = d->fixed;
> +       rate += ls1x_pll_rate_part(val, d->int_shift, d->int_width);
> +       if (d->frac_width)
> +               rate += ls1x_pll_rate_part(val, d->frac_shift, d->frac_width);
> +       rate *= parent_rate;
> +       rate >>= d->shift;
> +
> +       return rate;
> +}
> +
> +static const struct clk_ops ls1x_pll_clk_ops = {
> +       .recalc_rate = ls1x_pll_recalc_rate,
> +};
> +
> +static unsigned long ls1x_divider_recalc_rate(struct clk_hw *hw,
> +                                             unsigned long parent_rate)
> +{
> +       struct ls1x_clk *ls1x_clk = to_ls1x_clk(hw);
> +       const struct ls1x_clk_div_data *d = ls1x_clk->data;
> +       unsigned int val;
> +
> +       val = readl(ls1x_clk->reg) >> d->shift;
> +       val &= clk_div_mask(d->width);
> +
> +       return divider_recalc_rate(hw, parent_rate, val, d->table,
> +                                  d->flags, d->width);
> +}
> +
> +static long ls1x_divider_round_rate(struct clk_hw *hw, unsigned long rate,
> +                                   unsigned long *prate)
> +{
> +       struct ls1x_clk *ls1x_clk = to_ls1x_clk(hw);
> +       const struct ls1x_clk_div_data *d = ls1x_clk->data;
> +
> +       return divider_round_rate(hw, rate, prate, d->table,
> +                                 d->width, d->flags);
> +}
> +
> +static int ls1x_divider_set_rate(struct clk_hw *hw, unsigned long rate,
> +                                unsigned long parent_rate)
> +{
> +       struct ls1x_clk *ls1x_clk = to_ls1x_clk(hw);
> +       const struct ls1x_clk_div_data *d = ls1x_clk->data;
> +       int val, div_val;
> +       unsigned long flags = 0;
> +
> +       div_val = divider_get_val(rate, parent_rate, d->table,
> +                                 d->width, d->flags);
> +       if (div_val < 0)
> +               return div_val;
> +
> +       if (d->lock)
> +               spin_lock_irqsave(d->lock, flags);
> +       else
> +               __acquire(d->lock);
> +
> +       /* Bypass the clock */
> +       val = readl(ls1x_clk->reg);
> +       if (d->bypass_inv)
> +               val &= ~BIT(d->bypass_shift);
> +       else
> +               val |= BIT(d->bypass_shift);
> +       writel(val, ls1x_clk->reg);
> +
> +       val = readl(ls1x_clk->reg);
> +       val &= ~(clk_div_mask(d->width) << d->shift);
> +       val |= (u32)div_val << d->shift;
> +       writel(val, ls1x_clk->reg);
> +
> +       /* Restore the clock */
> +       val = readl(ls1x_clk->reg);
> +       if (d->bypass_inv)
> +               val |= BIT(d->bypass_shift);
> +       else
> +               val &= ~BIT(d->bypass_shift);
> +       writel(val, ls1x_clk->reg);
> +
> +       if (d->lock)
> +               spin_unlock_irqrestore(d->lock, flags);
> +       else
> +               __release(d->lock);

Is there a case where there isn't a lock? It would be easier to read if
this always had a lock and it wasn't optional.

> +
> +       return 0;
> +}
> +
> +static const struct clk_ops ls1x_clk_divider_ops = {
> +       .recalc_rate = ls1x_divider_recalc_rate,
> +       .round_rate = ls1x_divider_round_rate,
> +       .set_rate = ls1x_divider_set_rate,
> +};
> +
> +#define LS1X_CLK_PLL(_name, _offset, _fixed, _shift,                   \
> +                    f_shift, f_width, i_shift, i_width)                \
> +struct ls1x_clk _name = {                                              \
> +       .offset = (_offset),                                            \
> +       .data = &(struct ls1x_clk_pll_data) {                           \
> +               .fixed = (_fixed),                                      \
> +               .shift = (_shift),                                      \
> +               .int_shift = (i_shift),                                 \
> +               .int_width = (i_width),                                 \
> +               .frac_shift = (f_shift),                                \
> +               .frac_width = (f_width),                                \
> +       },                                                              \
> +       .hw.init = &(struct clk_init_data) {                            \
> +               .name = #_name,                                         \
> +               .ops = &ls1x_pll_clk_ops,                               \
> +               .parent_data = &(const struct clk_parent_data) {        \
> +                       .fw_name = "xtal",                              \
> +                       .name = "xtal",                                 \
> +                       .index = -1,                                    \
> +               },                                                      \
> +               .num_parents = 1,                                       \
> +       },                                                              \
> +}
> +
> +#define LS1X_CLK_DIV(_name, _pname, _offset, _shift, _width,           \
> +                    _table, _bypass_shift, _bypass_inv, _flags)        \
> +struct ls1x_clk _name = {                                              \
> +       .offset = (_offset),                                            \
> +       .data = &(struct ls1x_clk_div_data){                            \
> +               .shift = (_shift),                                      \
> +               .width = (_width),                                      \
> +               .table = (_table),                                      \
> +               .flags = (_flags),                                      \
> +               .bypass_shift = (_bypass_shift),                        \
> +               .bypass_inv = (_bypass_inv),                            \
> +               .lock = &ls1x_clk_div_lock,                             \
> +       },                                                              \
> +       .hw.init = &(struct clk_init_data) {                            \

Can be const.

> +               .name = #_name,                                         \
> +               .ops = &ls1x_clk_divider_ops,                           \
> +               .parent_hws = (const struct clk_hw *[]) { _pname },     \
> +               .num_parents = 1,                                       \
> +               .flags = CLK_GET_RATE_NOCACHE,                          \
> +       },                                                              \
> +}
> +
> +static LS1X_CLK_PLL(ls1b_clk_pll, CLK_PLL_FREQ, 12, 1, 0, 5, 0, 0);
> +static LS1X_CLK_DIV(ls1b_clk_cpu, &ls1b_clk_pll.hw, CLK_PLL_DIV,
> +                   20, 4, NULL, 8, 0,
> +                   CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ROUND_CLOSEST);
> +static LS1X_CLK_DIV(ls1b_clk_dc, &ls1b_clk_pll.hw, CLK_PLL_DIV,
> +                   26, 4, NULL, 12, 0, CLK_DIVIDER_ONE_BASED);
> +static LS1X_CLK_DIV(ls1b_clk_ahb, &ls1b_clk_pll.hw, CLK_PLL_DIV,
> +                   14, 4, NULL, 10, 0, CLK_DIVIDER_ONE_BASED);
> +static CLK_FIXED_FACTOR(ls1b_clk_apb, "ls1b_clk_apb", "ls1b_clk_ahb", 2, 1,
> +                       CLK_SET_RATE_PARENT);
> +
> +static struct clk_hw_onecell_data ls1b_clk_hw_data = {
> +       .hws = {
> +               [LS1X_CLKID_PLL] = &ls1b_clk_pll.hw,
> +               [LS1X_CLKID_CPU] = &ls1b_clk_cpu.hw,
> +               [LS1X_CLKID_DC] = &ls1b_clk_dc.hw,
> +               [LS1X_CLKID_AHB] = &ls1b_clk_ahb.hw,
> +               [LS1X_CLKID_APB] = &ls1b_clk_apb.hw,
> +               [CLK_NR_CLKS] = NULL,

Do you need a CLK_NR_CLKS sentinel entry?

> +       },
> +       .num = CLK_NR_CLKS,
> +};
> +
> +static const struct clk_div_table ls1c_ahb_div_table[] = {
> +       [0] = { .val = 0, .div = 2 },
> +       [1] = { .val = 1, .div = 4 },
> +       [2] = { .val = 2, .div = 3 },
> +       [3] = { .val = 3, .div = 3 },
> +       [4] = { /* sentinel */ }
> +};
> +
> +static LS1X_CLK_PLL(ls1c_clk_pll, CLK_PLL_FREQ, 0, 2, 8, 8, 16, 8);
> +static LS1X_CLK_DIV(ls1c_clk_cpu, &ls1c_clk_pll.hw, CLK_PLL_DIV,
> +                   8, 7, NULL, 0, 1,
> +                   CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ROUND_CLOSEST);
> +static LS1X_CLK_DIV(ls1c_clk_dc, &ls1c_clk_pll.hw, CLK_PLL_DIV,
> +                   24, 7, NULL, 4, 1, CLK_DIVIDER_ONE_BASED);
> +static LS1X_CLK_DIV(ls1c_clk_ahb, &ls1c_clk_cpu.hw, CLK_PLL_FREQ,
> +                   0, 2, ls1c_ahb_div_table, 0, 0, CLK_DIVIDER_ALLOW_ZERO);
> +static CLK_FIXED_FACTOR(ls1c_clk_apb, "ls1c_clk_apb", "ls1c_clk_ahb", 1, 1,
> +                       CLK_SET_RATE_PARENT);
> +
> +static struct clk_hw_onecell_data ls1c_clk_hw_data = {
> +       .hws = {
> +               [LS1X_CLKID_PLL] = &ls1c_clk_pll.hw,
> +               [LS1X_CLKID_CPU] = &ls1c_clk_cpu.hw,
> +               [LS1X_CLKID_DC] = &ls1c_clk_dc.hw,
> +               [LS1X_CLKID_AHB] = &ls1c_clk_ahb.hw,
> +               [LS1X_CLKID_APB] = &ls1c_clk_apb.hw,
> +               [CLK_NR_CLKS] = NULL,
> +       },
> +       .num = CLK_NR_CLKS,
> +};
> +
> +static void __init ls1x_clk_init(struct device_node *np,
> +                                struct clk_hw_onecell_data *hw_data)
> +{
> +       struct ls1x_clk *ls1x_clk;
> +       void __iomem *reg;
> +       int i, ret;
> +
> +       reg = of_iomap(np, 0);
> +       if (!reg) {
> +               pr_err("Unable to map base for %pOF\n", np);

Needs include.

> +               return;
> +       }
> +
> +       for (i = 0; i < CLK_NR_CLKS; i++) {
> +               /* array might be sparse */
> +               if (!hw_data->hws[i])
> +                       continue;
> +
> +               if (i != LS1X_CLKID_APB) {
> +                       ls1x_clk = to_ls1x_clk(hw_data->hws[i]);
> +                       ls1x_clk->reg = reg + ls1x_clk->offset;
> +               }
> +
> +               ret = of_clk_hw_register(np, hw_data->hws[i]);
> +               if (ret)
> +                       return;

unmap memory on failure? and unregister clks?

> +       }
> +
> +       ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, hw_data);
> +       if (ret)
> +               pr_err("Failed to register %pOF\n", np);

unmap memory on failure? And unregister clks?

> +}
> +
> +static void __init ls1b_clk_init(struct device_node *np)
> +{
> +       return ls1x_clk_init(np, &ls1b_clk_hw_data);
> +}
> +
> +static void __init ls1c_clk_init(struct device_node *np)
> +{
> +       return ls1x_clk_init(np, &ls1c_clk_hw_data);
> +}
> +
> +CLK_OF_DECLARE(ls1b_clk, "loongson,ls1b-clk", ls1b_clk_init);
> +CLK_OF_DECLARE(ls1c_clk, "loongson,ls1c-clk", ls1c_clk_init);

Any reason these can't be platform device drivers?

> +
> +MODULE_AUTHOR("Keguang Zhang <keguang.zhang@xxxxxxxxx>");
> +MODULE_DESCRIPTION("Loongson1 clock driver");

It's not a module. So these are useless macros. Drop them?