Re: [PATCH v3 5/7] clk: sunxi: add PRCM (Power/Reset/Clock Management) clks support

Emilio López
2014-05-13T15:10:30Z

Hi Boris,

First of all, thanks for working on this :)

While reading the code below I noticed a complete lack of comments. I
think it would be good to have at least some to aid readability,
considering these clocks are poorly documented on AW's material.

El 09/05/14 08:11, Boris BREZILLON escribió:
> The PRCM (Power/Reset/Clock Management) unit provides several clock
> devices:
> - AR100 clk: used to clock the Power Management co-processor
> - AHB0 clk: used to clock the AHB0 bus
> - APB0 clk and gates: used to clk peripherals connected to the APB0 bus
>
> Add support for these clks in a separate driver so that they can be probed
> as platform devices instead of registered during early init.
> This is needed to be able to probe PRCM MFD subdevices.
>
> Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
> Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> ---
> drivers/clk/sunxi/Makefile | 2 +
> drivers/clk/sunxi/clk-sun6i-prcm.c | 343 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 345 insertions(+)
> create mode 100644 drivers/clk/sunxi/clk-sun6i-prcm.c
>
> diff --git a/drivers/clk/sunxi/Makefile b/drivers/clk/sunxi/Makefile
> index b5bac91..ef8cdc9 100644
> --- a/drivers/clk/sunxi/Makefile
> +++ b/drivers/clk/sunxi/Makefile
> @@ -3,3 +3,5 @@
> #
>
> obj-y += clk-sunxi.o clk-factors.o
> +
> +obj-$(CONFIG_MFD_SUN6I_PRCM) += clk-sun6i-prcm.o
> diff --git a/drivers/clk/sunxi/clk-sun6i-prcm.c b/drivers/clk/sunxi/clk-sun6i-prcm.c
> new file mode 100644
> index 0000000..3efaf8f
> --- /dev/null
> +++ b/drivers/clk/sunxi/clk-sun6i-prcm.c
> @@ -0,0 +1,343 @@
> +/*
> + * Copyright (C) 2014 Free Electrons
> + *
> + * License Terms: GNU General Public License v2
> + * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
> + *
> + * Allwinner PRCM (Power/Reset/Clock Management) driver
> + *
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +
> +#define SUN6I_APB0_GATES_MAX_SIZE 32
> +#define SUN6I_AR100_MAX_PARENTS 4
> +#define SUN6I_AR100_SHIFT_MASK 0x3
> +#define SUN6I_AR100_SHIFT_MAX SUN6I_AR100_SHIFT_MASK
> +#define SUN6I_AR100_SHIFT_SHIFT 4
> +#define SUN6I_AR100_DIV_MASK 0x1f
> +#define SUN6I_AR100_DIV_MAX (SUN6I_AR100_DIV_MASK + 1)
> +#define SUN6I_AR100_DIV_SHIFT 8
> +#define SUN6I_AR100_MUX_MASK 0x3
> +#define SUN6I_AR100_MUX_SHIFT 16
> +
> +struct ar100_clk {
> + struct clk_hw hw;
> + void __iomem *reg;
> +};
> +
> +static inline struct ar100_clk *to_ar100_clk(struct clk_hw *hw)
> +{
> + return container_of(hw, struct ar100_clk, hw);
> +}
> +
> +static unsigned long ar100_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct ar100_clk *clk = to_ar100_clk(hw);
> + u32 val = readl(clk->reg);
> + int shift = (val >> SUN6I_AR100_SHIFT_SHIFT) & SUN6I_AR100_SHIFT_MASK;
> + int div = (val >> SUN6I_AR100_DIV_SHIFT) & SUN6I_AR100_DIV_MASK;
> +
> + return (parent_rate >> shift) / (div + 1);
> +}
> +
> +static long ar100_determine_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *best_parent_rate,
> + struct clk **best_parent_clk)
> +{
> + int nparents = __clk_get_num_parents(hw->clk);
> + long best_rate = -EINVAL;
> + int i;
> +
> + *best_parent_clk = NULL;
> +
> + for (i = 0; i < nparents; i++) {
> + unsigned long parent_rate;
> + unsigned long tmp_rate;
> + struct clk *parent;
> + unsigned long div;
> + int shift;
> +
> + parent = clk_get_parent_by_index(hw->clk, i);
> + parent_rate = __clk_get_rate(parent);
> + div = DIV_ROUND_UP(parent_rate, rate);
> +
> + shift = ffs(div) - 1;
> + if (shift > SUN6I_AR100_SHIFT_MAX)
> + shift = SUN6I_AR100_SHIFT_MAX;
> +
> + div >>= shift;
> +
> + while (div > SUN6I_AR100_DIV_MAX) {
> + shift++;
> + div >>= 1;
> + if (shift > SUN6I_AR100_SHIFT_MAX)
> + break;
> + }
> +
> + if (shift > SUN6I_AR100_SHIFT_MAX)
> + continue;
> +
> + tmp_rate = (parent_rate >> shift) / div;
> + if (!*best_parent_clk || tmp_rate > best_rate) {
> + *best_parent_clk = parent;
> + *best_parent_rate = parent_rate;
> + best_rate = tmp_rate;
> + }
> + }
> +
> + return best_rate;
> +}
> +
> +static int ar100_set_parent(struct clk_hw *hw, u8 index)
> +{
> + struct ar100_clk *clk = to_ar100_clk(hw);
> + u32 val = readl(clk->reg);
> +
> + if (index >= SUN6I_AR100_MAX_PARENTS)
> + return -EINVAL;
> +
> + val &= ~(SUN6I_AR100_MUX_MASK << SUN6I_AR100_MUX_SHIFT);
> + val |= (index << SUN6I_AR100_MUX_SHIFT);
> + writel(val, clk->reg);
> +
> + return 0;
> +}
> +
> +static u8 ar100_get_parent(struct clk_hw *hw)
> +{
> + struct ar100_clk *clk = to_ar100_clk(hw);
> + return (readl(clk->reg) >> SUN6I_AR100_MUX_SHIFT) &
> + SUN6I_AR100_MUX_MASK;
> +}
> +
> +static int ar100_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + unsigned long div = parent_rate / rate;
> + struct ar100_clk *clk = to_ar100_clk(hw);
> + u32 val = readl(clk->reg);
> + int shift;
> +
> + if (parent_rate % rate)
> + return -EINVAL;
> +
> + shift = ffs(div) - 1;
> + if (shift > SUN6I_AR100_SHIFT_MAX)
> + shift = SUN6I_AR100_SHIFT_MAX;
> +
> + div >>= shift;
> +
> + if (div > SUN6I_AR100_DIV_MAX)
> + return -EINVAL;
> +
> + val &= ~((SUN6I_AR100_SHIFT_MASK << SUN6I_AR100_SHIFT_SHIFT) |
> + (SUN6I_AR100_DIV_MASK << SUN6I_AR100_DIV_SHIFT));
> + val |= (shift << SUN6I_AR100_SHIFT_SHIFT) |
> + (div << SUN6I_AR100_DIV_SHIFT);
> + writel(val, clk->reg);
> +
> + return 0;
> +}
> +
> +struct clk_ops ar100_ops = {
> + .recalc_rate = ar100_recalc_rate,
> + .determine_rate = ar100_determine_rate,
> + .set_parent = ar100_set_parent,
> + .get_parent = ar100_get_parent,
> + .set_rate = ar100_set_rate,
> +};
> +
> +static int sun6i_a31_ar100_clk_register(struct platform_device *pdev)
> +{
> + const char *parents[SUN6I_AR100_MAX_PARENTS];
> + struct device_node *np = pdev->dev.of_node;
> + const char *clk_name = np->name;
> + struct clk_init_data init;
> + struct ar100_clk *ar100;
> + struct resource *r;
> + struct clk *clk;
> + int nparents;
> + int i;
> +
> + ar100 = devm_kzalloc(&pdev->dev, sizeof(*ar100), GFP_KERNEL);
> + if (!ar100)
> + return -ENOMEM;
> +
> + r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + ar100->reg = devm_ioremap_resource(&pdev->dev, r);
> + if (IS_ERR(ar100->reg))
> + return PTR_ERR(ar100->reg);
> +
> + nparents = of_clk_get_parent_count(np);
> + if (nparents > SUN6I_AR100_MAX_PARENTS)
> + nparents = SUN6I_AR100_MAX_PARENTS;
> +
> + for (i = 0; i < nparents; i++)
> + parents[i] = of_clk_get_parent_name(np, i);
> +
> + of_property_read_string(np, "clock-output-names", &clk_name);
> +
> + init.name = clk_name;
> + init.ops = &ar100_ops;
> + init.parent_names = parents;
> + init.num_parents = nparents;
> + init.flags = 0;
> +
> + ar100->hw.init = &init;
> +
> + clk = clk_register(&pdev->dev, &ar100->hw);
> + if (IS_ERR(clk))
> + return PTR_ERR(clk);
> +
> + return of_clk_add_provider(np, of_clk_src_simple_get, clk);
> +}
> +
> +static const struct clk_div_table sun6i_a31_apb0_divs[] = {
> + { .val = 0, .div = 2, },
> + { .val = 1, .div = 2, },
> + { .val = 2, .div = 4, },
> + { .val = 3, .div = 8, },
> + { /* sentinel */ },
> +};
> +
> +static int sun6i_a31_apb0_clk_register(struct platform_device *pdev)
> +{
> + struct device_node *np = pdev->dev.of_node;
> + const char *clk_name = np->name;
> + const char *clk_parent;
> + struct resource *r;
> + void __iomem *reg;
> + struct clk *clk;
> +
> + r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + reg = devm_ioremap_resource(&pdev->dev, r);
> + if (IS_ERR(reg))
> + return PTR_ERR(reg);
> +
> + clk_parent = of_clk_get_parent_name(np, 0);
> + if (!clk_parent)
> + return -EINVAL;

Indentation seems to be off here.

> +
> + of_property_read_string(np, "clock-output-names", &clk_name);
> +
> + clk = clk_register_divider_table(&pdev->dev, clk_name, clk_parent,
> + 0, reg, 0, 2, 0, sun6i_a31_apb0_divs,
> + NULL);
> + if (IS_ERR(clk))
> + return PTR_ERR(clk);
> +
> + return of_clk_add_provider(np, of_clk_src_simple_get, clk);
> +}
> +
> +static int sun6i_a31_apb0_gates_clk_register(struct platform_device *pdev)
> +{
> + struct device_node *np = pdev->dev.of_node;
> + struct clk_onecell_data *clk_data;
> + const char *clk_parent;
> + const char *clk_name;
> + struct resource *r;
> + void __iomem *reg;
> + int gate_id;
> + int ngates;
> + int i;
> +
> + r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + reg = devm_ioremap_resource(&pdev->dev, r);
> + if (!reg)
> + return PTR_ERR(reg);
> +
> + clk_parent = of_clk_get_parent_name(np, 0);
> + if (!clk_parent)
> + return -EINVAL;
> +
> + ngates = of_property_count_strings(np, "clock-output-names");
> + if (ngates < 0)
> + return ngates;
> +
> + if (!ngates || ngates > SUN6I_APB0_GATES_MAX_SIZE)
> + return -EINVAL;
> +
> + clk_data = devm_kzalloc(&pdev->dev, sizeof(struct clk_onecell_data),
> + GFP_KERNEL);
> + if (!clk_data)
> + return -ENOMEM;
> +
> + clk_data->clks = devm_kzalloc(&pdev->dev,
> + SUN6I_APB0_GATES_MAX_SIZE *
> + sizeof(struct clk *),
> + GFP_KERNEL);
> + if (!clk_data->clks)
> + return -ENOMEM;
> +
> + for (i = 0; i < ngates; i++) {
> + of_property_read_string_index(np, "clock-output-names",
> + i, &clk_name);
> +
> + gate_id = i;
> + of_property_read_u32_index(np, "clock-indices", i, &gate_id);
> +
> + WARN_ON(gate_id >= SUN6I_APB0_GATES_MAX_SIZE);
> + if (gate_id >= SUN6I_APB0_GATES_MAX_SIZE)
> + continue;
> +
> + clk_data->clks[gate_id] = clk_register_gate(&pdev->dev,
> + clk_name,
> + clk_parent, 0,
> + reg, gate_id,
> + 0, NULL);
> + WARN_ON(IS_ERR(clk_data->clks[gate_id]));
> + }
> +
> + clk_data->clk_num = ngates;
> +
> + return of_clk_add_provider(np, of_clk_src_onecell_get, clk_data);
> +}
> +
> +const struct of_device_id sun6i_a31_prcm_clk_dt_ids[] = {
> + {
> + .compatible = "allwinner,sun6i-a31-ar100-clk",
> + .data = sun6i_a31_ar100_clk_register,
> + },
> + {
> + .compatible = "allwinner,sun6i-a31-apb0-clk",
> + .data = sun6i_a31_apb0_clk_register,
> + },
> + {
> + .compatible = "allwinner,sun6i-a31-apb0-gates-clk",
> + .data = sun6i_a31_apb0_gates_clk_register,
> + },
> + { /* sentinel */ }
> +};
> +
> +static int sun6i_a31_prcm_clk_probe(struct platform_device *pdev)
> +{
> + struct device_node *np = pdev->dev.of_node;
> + int (*register_func)(struct platform_device *pdev);
> + const struct of_device_id *match;
> +
> + match = of_match_node(sun6i_a31_prcm_clk_dt_ids, np);
> + if (!match)
> + return -EINVAL;
> +
> + register_func = match->data;
> + return register_func(pdev);
> +}
> +
> +static struct platform_driver sun6i_a31_prcm_clk_driver = {
> + .driver = {
> + .name = "sun6i-a31-prcm-clk",
> + .owner = THIS_MODULE,
> + .of_match_table = sun6i_a31_prcm_clk_dt_ids,
> + },
> + .probe = sun6i_a31_prcm_clk_probe,
> +};
> +module_platform_driver(sun6i_a31_prcm_clk_driver);
> +
> +MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>");
> +MODULE_DESCRIPTION("Allwinner PRCM clock Driver");
> +MODULE_LICENSE("GPL v2");

Other than that, the code looks good to me. As we're nearing the merge
window and you need this for other drivers, let me know if you want me
to apply this and fixup the extra tab locally, or if you wish to respin
this patch with some more comments.

@Mike, any comments on this?

Cheers,

Emilio