Re: [PATCH V3 3/8] clk: qcom: Add A53 PLL support for ipq6018 devices

[Stephen Boyd <sboyd@kernel.org>]

Quoting Sivaprakash Murugesan (2020-04-13 19:55:17)
> The CPUs on Qualcomm IPQ6018 platform is primarily clocked by A53 PLL.
> This patch adds support for the A53 PLL on IPQ6018 devices which can
> support CPU frequencies above 1Ghz.
> 
> Signed-off-by: Sivaprakash Murugesan <sivaprak@codeaurora.org>
> ---
>  drivers/clk/qcom/a53-pll.c | 136 ++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 111 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/clk/qcom/a53-pll.c b/drivers/clk/qcom/a53-pll.c
> index 45cfc57..a95351c 100644
> --- a/drivers/clk/qcom/a53-pll.c
> +++ b/drivers/clk/qcom/a53-pll.c
> @@ -11,11 +11,40 @@
>  #include <linux/platform_device.h>
>  #include <linux/regmap.h>
>  #include <linux/module.h>
> +#include <linux/of_device.h>

Why does this driver need to change to use of_device APIs?

>  
>  #include "clk-pll.h"
>  #include "clk-regmap.h"
> +#include "clk-alpha-pll.h"
>  
> -static const struct pll_freq_tbl a53pll_freq[] = {
> +struct a53_alpha_pll {
> +       struct alpha_pll_config *pll_config;
> +       struct clk_alpha_pll *pll;
> +};
> +
> +union a53pll {
> +       struct clk_pll *pll;
> +       struct a53_alpha_pll alpha_pll;
> +};
> +
> +struct a53pll_data {
> +#define PLL_IS_ALPHA BIT(0)
> +       u8 flags;
> +       union a53pll a53pll;

Why is there a union? Can't we have different clk ops for the two types
of PLLs and then use container_of to get it from the clk ops?

> +};
> +
> +static const u8 ipq_pll_offsets[] = {
> +       [PLL_OFF_L_VAL] = 0x08,
> +       [PLL_OFF_ALPHA_VAL] = 0x10,
> +       [PLL_OFF_USER_CTL] = 0x18,
> +       [PLL_OFF_CONFIG_CTL] = 0x20,
> +       [PLL_OFF_CONFIG_CTL_U] = 0x24,
> +       [PLL_OFF_STATUS] = 0x28,
> +       [PLL_OFF_TEST_CTL] = 0x30,
> +       [PLL_OFF_TEST_CTL_U] = 0x34,
> +};
> +
> +static const struct pll_freq_tbl msm8996_a53pll_freq[] = {
>         {  998400000, 52, 0x0, 0x1, 0 },
>         { 1094400000, 57, 0x0, 0x1, 0 },
>         { 1152000000, 62, 0x0, 0x1, 0 },
> @@ -26,6 +55,64 @@ static const struct pll_freq_tbl a53pll_freq[] = {
>         { }
>  };
>  
> +static struct clk_pll msm8996_pll = {
> +       .mode_reg = 0x0,
> +       .l_reg = 0x04,
> +       .m_reg = 0x08,
> +       .n_reg = 0x0c,
> +       .config_reg = 0x14,
> +       .status_reg = 0x1c,
> +       .status_bit = 16,
> +       .freq_tbl = msm8996_a53pll_freq,
> +       .clkr.hw.init = &(struct clk_init_data){
> +               .name = "a53pll",
> +               .flags = CLK_IS_CRITICAL,
> +               .parent_data = &(const struct clk_parent_data){
> +                       .fw_name = "xo",
> +                       .name = "xo",
> +               },
> +               .num_parents = 1,
> +               .ops = &clk_pll_sr2_ops,
> +       },
> +};
> +
> +static struct clk_alpha_pll ipq6018_pll = {
> +       .offset = 0x0,
> +       .regs = ipq_pll_offsets,
> +       .flags = SUPPORTS_DYNAMIC_UPDATE,
> +       .clkr = {
> +               .enable_reg = 0x0,
> +               .enable_mask = BIT(0),
> +               .hw.init = &(struct clk_init_data){
> +                       .name = "a53pll",
> +                       .flags = CLK_IS_CRITICAL,
> +                       .parent_data = &(const struct clk_parent_data){
> +                               .fw_name = "xo",
> +                       },
> +                       .num_parents = 1,
> +                       .ops = &clk_alpha_pll_huayra_ops,
> +               },
> +       },
> +};
> +
> +static struct alpha_pll_config ipq6018_pll_config = {

Can this be const?

> +       .l = 0x37,
> +       .config_ctl_val = 0x04141200,
> +       .config_ctl_hi_val = 0x0,
> +       .early_output_mask = BIT(3),
> +       .main_output_mask = BIT(0),
> +};
> +
> +static struct a53pll_data msm8996pll_data = {
> +       .a53pll.pll = &msm8996_pll,
> +};
> +
> +static struct a53pll_data ipq6018pll_data = {
> +       .flags = PLL_IS_ALPHA,
> +       .a53pll.alpha_pll.pll = &ipq6018_pll,
> +       .a53pll.alpha_pll.pll_config = &ipq6018_pll_config,
> +};
> +
>  static const struct regmap_config a53pll_regmap_config = {
>         .reg_bits               = 32,
>         .reg_stride             = 4,
> @@ -39,14 +126,16 @@ static int qcom_a53pll_probe(struct platform_device *pdev)
>         struct device *dev = &pdev->dev;
>         struct regmap *regmap;
>         struct resource *res;
> -       struct clk_pll *pll;
> +       const struct a53pll_data *pll_data;
> +       struct clk_regmap *clkr;
>         void __iomem *base;
> -       struct clk_init_data init = { };
>         int ret;
>  
> -       pll = devm_kzalloc(dev, sizeof(*pll), GFP_KERNEL);
> -       if (!pll)
> -               return -ENOMEM;
> +       pll_data = of_device_get_match_data(dev);

Use device_get_match_data() please.

> +       if (!pll_data) {
> +               dev_err(dev, "failed to get platform data\n");

No error message please.

> +               return -ENODEV;
> +       }
>  
>         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>         base = devm_ioremap_resource(dev, res);
> @@ -57,30 +146,26 @@ static int qcom_a53pll_probe(struct platform_device *pdev)
>         if (IS_ERR(regmap))
>                 return PTR_ERR(regmap);
>  
> -       pll->l_reg = 0x04;
> -       pll->m_reg = 0x08;
> -       pll->n_reg = 0x0c;
> -       pll->config_reg = 0x14;
> -       pll->mode_reg = 0x00;
> -       pll->status_reg = 0x1c;
> -       pll->status_bit = 16;
> -       pll->freq_tbl = a53pll_freq;
> -
> -       init.name = "a53pll";
> -       init.parent_names = (const char *[]){ "xo" };
> -       init.num_parents = 1;
> -       init.ops = &clk_pll_sr2_ops;
> -       init.flags = CLK_IS_CRITICAL;

Please document why a clk is critical.

> -       pll->clkr.hw.init = &init;
> -
> -       ret = devm_clk_register_regmap(dev, &pll->clkr);
> +       if (pll_data->flags & PLL_IS_ALPHA) {
> +               struct clk_alpha_pll *alpha_pll =
> +                       pll_data->a53pll.alpha_pll.pll;
> +               struct alpha_pll_config *alpha_pll_config =
> +                       pll_data->a53pll.alpha_pll.pll_config;
> +
> +               clk_alpha_pll_configure(alpha_pll, regmap, alpha_pll_config);
> +               clkr = &pll_data->a53pll.alpha_pll.pll->clkr;
> +       } else {
> +               clkr = &pll_data->a53pll.pll->clkr;
> +       }

Sorry, the design is confusing.