Message-ID: <160453799538.3965362.16773121624590810076@swboyd.mtv.corp.google.com>
Date:   Wed, 04 Nov 2020 16:59:55 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Abel Vesa <abel.vesa@....com>, Adam Ford <aford173@...il.com>,
        Anson Huang <anson.huang@....com>,
        Dong Aisheng <aisheng.dong@....com>,
        Fabio Estevam <fabio.estevam@....com>,
        Jacky Bai <ping.bai@....com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Marek Vasut <marek.vasut@...il.com>,
        Mike Turquette <mturquette@...libre.com>,
        Peng Fan <peng.fan@....com>, Rob Herring <robh@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>
Cc:     NXP Linux Team <linux-imx@....com>,
        linux-arm-kernel@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        Abel Vesa <abel.vesa@....com>
Subject: Re: [PATCH v5 10/14] clk: imx: Add generic blk-ctl driver

Quoting Abel Vesa (2020-11-03 03:18:22)
> diff --git a/drivers/clk/imx/clk-blk-ctl.c b/drivers/clk/imx/clk-blk-ctl.c
> new file mode 100644
> index 00000000..9ac0ed0
> --- /dev/null
> +++ b/drivers/clk/imx/clk-blk-ctl.c
> @@ -0,0 +1,302 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright 2020 NXP.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/reset-controller.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <linux/types.h>
> +
> +#include "clk.h"
> +#include "clk-blk-ctl.h"
> +
> +struct imx_reset_hw {
> +       u32 offset;
> +       u32 shift;
> +       u32 mask;
> +       unsigned long asserted;
> +};
> +
> +struct imx_pm_safekeep_info {
> +       uint32_t *regs_values;
> +       uint32_t *regs_offsets;

Please use u32, it's shorter and kernel style.

> +       uint32_t regs_num;
> +};
> +
> +struct imx_blk_ctl_drvdata {
> +       void __iomem *base;
> +       struct reset_controller_dev rcdev;
> +       struct imx_reset_hw *rst_hws;
> +       struct imx_pm_safekeep_info pm_info;
> +
> +       spinlock_t lock;
> +};
> +
> +static void __maybe_unused imx_blk_ctl_read_write(struct device *dev,
> +                                                       bool write)
> +{
> +       struct imx_blk_ctl_drvdata *drvdata = dev_get_drvdata(dev);
> +       struct imx_pm_safekeep_info *pm_info = &drvdata->pm_info;
> +       void __iomem *base = drvdata->base;
> +       int i;
> +
> +       if (!pm_info->regs_num)
> +               return;
> +
> +       for (i = 0; i < pm_info->regs_num; i++) {
> +               u32 offset = pm_info->regs_offsets[i];
> +
> +               if (write)
> +                       writel(pm_info->regs_values[i], base + offset);
> +               else
> +                       pm_info->regs_values[i] = readl(base + offset);
> +       }
> +
> +}
> +
> +static int __maybe_unused imx_blk_ctl_runtime_suspend(struct device *dev)
> +{
> +       imx_blk_ctl_read_write(dev, false);
> +
> +       return 0;
> +}
> +
> +static int __maybe_unused imx_blk_ctl_runtime_resume(struct device *dev)
> +{
> +       imx_blk_ctl_read_write(dev, true);
> +
> +       return 0;
> +}
> +
> +const struct dev_pm_ops imx_blk_ctl_pm_ops = {
> +       SET_RUNTIME_PM_OPS(imx_blk_ctl_runtime_suspend,
> +                          imx_blk_ctl_runtime_resume, NULL)
> +       SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> +                          pm_runtime_force_resume)
> +};
> +EXPORT_SYMBOL_GPL(imx_blk_ctl_pm_ops);
> +
> +static int imx_blk_ctl_reset_set(struct reset_controller_dev *rcdev,
> +                                 unsigned long id, bool assert)
> +{
> +       struct imx_blk_ctl_drvdata *drvdata = container_of(rcdev,
> +                       struct imx_blk_ctl_drvdata, rcdev);
> +       unsigned int offset = drvdata->rst_hws[id].offset;
> +       unsigned int shift = drvdata->rst_hws[id].shift;
> +       unsigned int mask = drvdata->rst_hws[id].mask;
> +       void __iomem *reg_addr = drvdata->base + offset;
> +       unsigned long flags;
> +       u32 reg;
> +
> +       if (!assert && !test_bit(1, &drvdata->rst_hws[id].asserted))
> +               return -ENODEV;
> +
> +       if (assert && !test_and_set_bit(1, &drvdata->rst_hws[id].asserted))

We are testing the same bit atomically, twice. At a quick glance this
code looks broken. But then looking closer it's being multiplexed. Can
we move these assert/!assert checks to the caller? It will make it
easier to reason about.

Is the atomic-ness of this code important? If not, it should use
__test_bit() and __test_and_set_bit() because locking is being handled
somewhere higher up. Furthermore, why are we using a per-reset bitmap to
set one bit? Either combine them into one bitmap or have a simple bool
please.

> +               pm_runtime_get_sync(rcdev->dev);
> +
> +       spin_lock_irqsave(&drvdata->lock, flags);
> +
> +       reg = readl(reg_addr);
> +       if (assert)
> +               writel(reg & ~(mask << shift), reg_addr);
> +       else
> +               writel(reg | (mask << shift), reg_addr);
> +
> +       spin_unlock_irqrestore(&drvdata->lock, flags);
> +
> +       if (!assert && test_and_clear_bit(1, &drvdata->rst_hws[id].asserted))
> +               pm_runtime_put(rcdev->dev);
> +

Same comment here.

> +       return 0;
> +}
> +
> +static int imx_blk_ctl_reset_assert(struct reset_controller_dev *rcdev,
> +                                          unsigned long id)
> +{
> +       return imx_blk_ctl_reset_set(rcdev, id, true);
> +}
> +
> +static int imx_blk_ctl_reset_deassert(struct reset_controller_dev *rcdev,
> +                                            unsigned long id)
> +{
> +       return imx_blk_ctl_reset_set(rcdev, id, false);
> +}
> +
> +static const struct reset_control_ops imx_blk_ctl_reset_ops = {
> +       .assert         = imx_blk_ctl_reset_assert,
> +       .deassert       = imx_blk_ctl_reset_deassert,
> +};
> +
> +static int imx_blk_ctl_register_reset_controller(struct device *dev)
> +{
> +       const struct imx_blk_ctl_dev_data *dev_data = of_device_get_match_data(dev);
> +       struct imx_blk_ctl_drvdata *drvdata = dev_get_drvdata(dev);
> +       int max = dev_data->resets_max;
> +       struct imx_reset_hw *hws;
> +       int i;
> +
> +       spin_lock_init(&drvdata->lock);
> +
> +       drvdata->rcdev.owner     = THIS_MODULE;
> +       drvdata->rcdev.nr_resets = max;
> +       drvdata->rcdev.ops       = &imx_blk_ctl_reset_ops;
> +       drvdata->rcdev.of_node   = dev->of_node;
> +       drvdata->rcdev.dev       = dev;
> +
> +       drvdata->rst_hws = devm_kcalloc(dev, max, sizeof(struct imx_reset_hw),
> +                                       GFP_KERNEL);
> +       hws = drvdata->rst_hws;
> +
> +       for (i = 0; i < dev_data->hws_num; i++) {
> +               struct imx_blk_ctl_hw *hw = &dev_data->hws[i];
> +
> +               if (hw->type != BLK_CTL_RESET)
> +                       continue;
> +
> +               hws[hw->id].offset = hw->offset;
> +               hws[hw->id].shift = hw->shift;
> +               hws[hw->id].mask = hw->mask;
> +       }
> +
> +       return devm_reset_controller_register(dev, &drvdata->rcdev);
> +}

Nitpick: Add a newline here please

> +static struct clk_hw *imx_blk_ctl_register_one_clock(struct device *dev,
> +                                               struct imx_blk_ctl_hw *hw)
> +{
> +       struct imx_blk_ctl_drvdata *drvdata = dev_get_drvdata(dev);
> +       void __iomem *base = drvdata->base;
> +       struct clk_hw *clk_hw = NULL;

Is this necessary? Please add a default to the case if so and drop this
assignment. But if all hw->type are covered in the case statement then
this assignment can be dropped and nothing else. The compiler should
tell us we forgot to handle a case.

> +
> +       switch (hw->type) {
> +       case BLK_CTL_CLK_MUX:
> +               clk_hw = imx_dev_clk_hw_mux_flags(dev, hw->name,
> +                                                 base + hw->offset,
> +                                                 hw->shift, hw->width,
> +                                                 hw->parents,
> +                                                 hw->parents_count,
> +                                                 hw->flags);
> +               break;
> +       case BLK_CTL_CLK_GATE:
> +               clk_hw = imx_dev_clk_hw_gate(dev, hw->name, hw->parents,
> +                                            base + hw->offset, hw->shift);
> +               break;
> +       case BLK_CTL_CLK_SHARED_GATE:
> +               clk_hw = imx_dev_clk_hw_gate_shared(dev, hw->name,
> +                                                   hw->parents,
> +                                                   base + hw->offset,
> +                                                   hw->shift,
> +                                                   hw->shared_count);
> +               break;
> +       case BLK_CTL_CLK_PLL14XX:
> +               clk_hw = imx_dev_clk_hw_pll14xx(dev, hw->name, hw->parents,
> +                                               base + hw->offset, hw->pll_tbl);
> +               break;
> +       };
> +
> +       return clk_hw;
> +}
> +
> +static int imx_blk_ctl_register_clock_controller(struct device *dev)
> +{
> +       const struct imx_blk_ctl_dev_data *dev_data = of_device_get_match_data(dev);
> +       struct clk_hw_onecell_data *clk_hw_data;
> +       struct clk_hw **hws;
> +       int i;
> +
> +       clk_hw_data = devm_kzalloc(dev, struct_size(clk_hw_data, hws,
> +                               dev_data->hws_num), GFP_KERNEL);
> +       if (WARN_ON(!clk_hw_data))

We can drop the WARN_ON() call, slab allocations already print a
stacktrace.

> +               return -ENOMEM;
> +
> +       clk_hw_data->num = dev_data->clocks_max;
> +       hws = clk_hw_data->hws;
> +
> +       for (i = 0; i < dev_data->hws_num; i++) {
> +               struct imx_blk_ctl_hw *hw = &dev_data->hws[i];
> +

Add a comment like /* Resets aren't a clk */

> +               if (hw->type == BLK_CTL_RESET)
> +                       continue;
> +
> +               hws[hw->id] = imx_blk_ctl_register_one_clock(dev, hw);
> +       }
> +
> +       imx_check_clk_hws(hws, dev_data->clocks_max);
> +
> +       return of_clk_add_hw_provider(dev->of_node, of_clk_hw_onecell_get,
> +                                       clk_hw_data);
> +}
> +
> +static int imx_blk_ctl_init_runtime_pm_safekeeping(struct device *dev)
> +{
> +       const struct imx_blk_ctl_dev_data *dev_data = of_device_get_match_data(dev);
> +       struct imx_blk_ctl_drvdata *drvdata = dev_get_drvdata(dev);
> +       struct imx_pm_safekeep_info *pm_info = &drvdata->pm_info;
> +       u32 regs_num = dev_data->pm_runtime_saved_regs_num;
> +       const u32 *regs_offsets = dev_data->pm_runtime_saved_regs;
> +
> +       if (!dev_data->pm_runtime_saved_regs_num)
> +               return 0;
> +
> +       pm_info->regs_values = devm_kzalloc(dev,
> +                                           sizeof(u32) * regs_num,
> +                                           GFP_KERNEL);
> +       if (WARN_ON(IS_ERR(pm_info->regs_values)))

Please drop WARN_ON

> +               return PTR_ERR(pm_info->regs_values);
> +
> +       pm_info->regs_offsets = kmemdup(regs_offsets,
> +                                       regs_num * sizeof(u32), GFP_KERNEL);
> +       if (WARN_ON(IS_ERR(pm_info->regs_offsets)))

Please drop WARN_ON

> +               return PTR_ERR(pm_info->regs_offsets);
> +
> +       pm_info->regs_num = regs_num;
> +
> +       return 0;
> +}
> +
> +int imx_blk_ctl_register(struct platform_device *pdev)
> +{
> +       struct imx_blk_ctl_drvdata *drvdata;
> +       struct device *dev = &pdev->dev;
> +       int ret;
> +
> +       drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> +       if (WARN_ON(!drvdata))

Please drop WARN_ON

> +               return -ENOMEM;
> +
> +       drvdata->base = devm_platform_ioremap_resource(pdev, 0);
> +       if (WARN_ON(IS_ERR(drvdata->base)))

Please drop WARN_ON

> +               return PTR_ERR(drvdata->base);
> +
> +       dev_set_drvdata(dev, drvdata);
> +
> +       ret = imx_blk_ctl_init_runtime_pm_safekeeping(dev);
> +       if (ret)
> +               return ret;
> +
> +       pm_runtime_get_noresume(dev);
> +       pm_runtime_set_active(dev);
> +       pm_runtime_enable(dev);
> +
> +       ret = imx_blk_ctl_register_clock_controller(dev);
> +       if (ret) {
> +               pm_runtime_put(dev);
> +               return ret;
> +       }
> +
> +       ret = imx_blk_ctl_register_reset_controller(dev);
> +
> +       pm_runtime_put(dev);
> +
> +       return ret;
> +}
> +EXPORT_SYMBOL_GPL(imx_blk_ctl_register);
> diff --git a/drivers/clk/imx/clk-blk-ctl.h b/drivers/clk/imx/clk-blk-ctl.h
> new file mode 100644
> index 00000000..3f14a47
> --- /dev/null
> +++ b/drivers/clk/imx/clk-blk-ctl.h
> @@ -0,0 +1,80 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __MACH_IMX_CLK_BLK_CTL_H
> +#define __MACH_IMX_CLK_BLK_CTL_H
> +
> +enum imx_blk_ctl_hw_type {
> +       BLK_CTL_CLK_MUX,
> +       BLK_CTL_CLK_GATE,
> +       BLK_CTL_CLK_SHARED_GATE,
> +       BLK_CTL_CLK_PLL14XX,
> +       BLK_CTL_RESET,
> +};
> +
> +struct imx_blk_ctl_hw {
> +       int type;
> +       char *name;
> +       u32 offset;
> +       u32 shift;
> +       u32 mask;
> +       u32 width;
> +       u32 flags;
> +       u32 id;
> +       const void *parents;
> +       u32 parents_count;
> +       int *shared_count;
> +       const struct imx_pll14xx_clk *pll_tbl;

Please forward declare pointer types.

> +};
> +
> +struct imx_blk_ctl_dev_data {
> +       struct imx_blk_ctl_hw *hws;

Please forward declare pointer types.

> +       u32 hws_num;
> +
> +       u32 clocks_max;
> +       u32 resets_max;
> +
> +       u32 pm_runtime_saved_regs_num;
> +       u32 pm_runtime_saved_regs[];
> +};
> +
> +#define IMX_BLK_CTL(_type, _name, _id, _offset, _shift, _width, _mask, _parents, _parents_count, _flags, sh_count, _pll_tbl) \
> +       {                                               \
> +               .type = _type,                          \
> +               .name = _name,                          \
> +               .id = _id,                              \
> +               .offset = _offset,                      \
> +               .shift = _shift,                        \
> +               .width = _width,                        \
> +               .mask = _mask,                          \
> +               .parents = _parents,                    \
> +               .parents_count = _parents_count,        \
> +               .flags = _flags,                        \
> +               .shared_count = sh_count,               \
> +               .pll_tbl = _pll_tbl,                    \
> +       }
> +
> +#define IMX_BLK_CTL_CLK_MUX(_name, _id, _offset, _shift, _width, _parents) \
> +       IMX_BLK_CTL(BLK_CTL_CLK_MUX, _name, _id, _offset, _shift, _width, 0, _parents, ARRAY_SIZE(_parents), 0, NULL, NULL)
> +
> +#define IMX_BLK_CTL_CLK_MUX_FLAGS(_name, _id, _offset, _shift, _width, _parents, _flags) \
> +       IMX_BLK_CTL(BLK_CTL_CLK_MUX, _name, _id, _offset, _shift, _width, 0, _parents, ARRAY_SIZE(_parents), _flags, NULL, NULL)
> +
> +#define IMX_BLK_CTL_CLK_GATE(_name, _id, _offset, _shift, _parents) \
> +       IMX_BLK_CTL(BLK_CTL_CLK_GATE, _name, _id, _offset, _shift, 1, 0, _parents, 1, 0, NULL, NULL)
> +
> +#define IMX_BLK_CTL_CLK_SHARED_GATE(_name, _id, _offset, _shift, _parents, sh_count) \
> +       IMX_BLK_CTL(BLK_CTL_CLK_SHARED_GATE, _name, _id, _offset, _shift, 1, 0, _parents, 1, 0, sh_count, NULL)
> +
> +#define IMX_BLK_CTL_CLK_PLL14XX(_name, _id, _offset, _parents, _pll_tbl) \
> +       IMX_BLK_CTL(BLK_CTL_CLK_PLL14XX, _name, _id, _offset, 0, 0, 0, _parents, 1, 0, NULL, _pll_tbl)
> +
> +#define IMX_BLK_CTL_RESET(_id, _offset, _shift) \
> +       IMX_BLK_CTL(BLK_CTL_RESET, NULL, _id, _offset, _shift, 0, 1, NULL, 0, 0, NULL, NULL)
> +
> +#define IMX_BLK_CTL_RESET_MASK(_id, _offset, _shift, mask) \
> +       IMX_BLK_CTL(BLK_CTL_RESET, NULL, _id, _offset, _shift, 0, mask, NULL, 0, 0, NULL, NULL)
> +
> +extern const struct dev_pm_ops imx_blk_ctl_pm_ops;
> +
> +int imx_blk_ctl_register(struct platform_device *pdev);

Please forward declare pointer types.

> +
> +#endif
> -- 
> 2.7.4
>

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