Re: [PATCH 3/3] soc: fsl: add RCPM driver

[Rafael J. Wysocki]

On Tue, Oct 22, 2019 at 9:52 AM Ran Wang <ran.wang_1@xxxxxxx> wrote:
>
> The NXP's QorIQ Processors based on ARM Core have RCPM module
> (Run Control and Power Management), which performs system level
> tasks associated with power management such as wakeup source control.
>
> This driver depends on PM wakeup source framework which help to
> collect wake information.
>
> Signed-off-by: Ran Wang <ran.wang_1@xxxxxxx>
> ---
> Change in v8:
>         - Adjust related API usage to meet wakeup.c's update in patch 1/3.
>         - Add sanity checking for the case of ws->dev or ws->dev->parent
>           is null.
>
> Change in v7:
>         - Replace 'ws->dev' with 'ws->dev->parent' to get aligned with
>         c8377adfa781 ("PM / wakeup: Show wakeup sources stats in sysfs")
>         - Remove '+obj-y += ftm_alarm.o' since it is wrong.
>         - Cosmetic work.
>
> Change in v6:
>         - Adjust related API usage to meet wakeup.c's update in patch 1/3.
>
> Change in v5:
>         - Fix v4 regression of the return value of wakeup_source_get_next()
>         didn't pass to ws in while loop.
>         - Rename wakeup_source member 'attached_dev' to 'dev'.
>         - Rename property 'fsl,#rcpm-wakeup-cells' to '#fsl,rcpm-wakeup-cells'.
>         please see https://lore.kernel.org/patchwork/patch/1101022/
>
> Change in v4:
>         - Remove extra ',' in author line of rcpm.c
>         - Update usage of wakeup_source_get_next() to be less confusing to the
> reader, code logic remain the same.
>
> Change in v3:
>         - Some whitespace ajdustment.
>
> Change in v2:
>         - Rebase Kconfig and Makefile update to latest mainline.
>
>  drivers/soc/fsl/Kconfig  |   8 +++
>  drivers/soc/fsl/Makefile |   1 +
>  drivers/soc/fsl/rcpm.c   | 133 +++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 142 insertions(+)
>  create mode 100644 drivers/soc/fsl/rcpm.c
>
> diff --git a/drivers/soc/fsl/Kconfig b/drivers/soc/fsl/Kconfig
> index f9ad8ad..4918856 100644
> --- a/drivers/soc/fsl/Kconfig
> +++ b/drivers/soc/fsl/Kconfig
> @@ -40,4 +40,12 @@ config DPAA2_CONSOLE
>           /dev/dpaa2_mc_console and /dev/dpaa2_aiop_console,
>           which can be used to dump the Management Complex and AIOP
>           firmware logs.
> +
> +config FSL_RCPM
> +       bool "Freescale RCPM support"
> +       depends on PM_SLEEP
> +       help
> +         The NXP QorIQ Processors based on ARM Core have RCPM module
> +         (Run Control and Power Management), which performs all device-level
> +         tasks associated with power management, such as wakeup source control.
>  endmenu
> diff --git a/drivers/soc/fsl/Makefile b/drivers/soc/fsl/Makefile
> index 71dee8d..906f1cd 100644
> --- a/drivers/soc/fsl/Makefile
> +++ b/drivers/soc/fsl/Makefile
> @@ -6,6 +6,7 @@
>  obj-$(CONFIG_FSL_DPAA)                 += qbman/
>  obj-$(CONFIG_QUICC_ENGINE)             += qe/
>  obj-$(CONFIG_CPM)                      += qe/
> +obj-$(CONFIG_FSL_RCPM)                 += rcpm.o
>  obj-$(CONFIG_FSL_GUTS)                 += guts.o
>  obj-$(CONFIG_FSL_MC_DPIO)              += dpio/
>  obj-$(CONFIG_DPAA2_CONSOLE)            += dpaa2-console.o
> diff --git a/drivers/soc/fsl/rcpm.c b/drivers/soc/fsl/rcpm.c
> new file mode 100644
> index 0000000..3ed135e
> --- /dev/null
> +++ b/drivers/soc/fsl/rcpm.c
> @@ -0,0 +1,133 @@
> +// SPDX-License-Identifier: GPL-2.0
> +//
> +// rcpm.c - Freescale QorIQ RCPM driver
> +//
> +// Copyright 2019 NXP
> +//
> +// Author: Ran Wang <ran.wang_1@xxxxxxx>
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/of_address.h>
> +#include <linux/slab.h>
> +#include <linux/suspend.h>
> +#include <linux/kernel.h>
> +
> +#define RCPM_WAKEUP_CELL_MAX_SIZE      7
> +
> +struct rcpm {
> +       unsigned int    wakeup_cells;
> +       void __iomem    *ippdexpcr_base;
> +       bool            little_endian;
> +};
> +

Please add a kerneldoc comment describing this routine.

> +static int rcpm_pm_prepare(struct device *dev)
> +{
> +       int i, ret, idx;
> +       void __iomem *base;
> +       struct wakeup_source    *ws;
> +       struct rcpm             *rcpm;
> +       struct device_node      *np = dev->of_node;
> +       u32 value[RCPM_WAKEUP_CELL_MAX_SIZE + 1], tmp;
> +
> +       rcpm = dev_get_drvdata(dev);
> +       if (!rcpm)
> +               return -EINVAL;
> +
> +       base = rcpm->ippdexpcr_base;
> +       idx = wakeup_sources_read_lock();
> +
> +       /* Begin with first registered wakeup source */
> +       for_each_wakeup_source(ws) {
> +
> +               /* skip object which is not attached to device */
> +               if (!ws->dev || !ws->dev->parent)
> +                       continue;
> +
> +               ret = device_property_read_u32_array(ws->dev->parent,
> +                               "fsl,rcpm-wakeup", value,
> +                               rcpm->wakeup_cells + 1);
> +
> +               /*  Wakeup source should refer to current rcpm device */
> +               if (ret || (np->phandle != value[0])) {
> +                       dev_info(dev, "%s doesn't refer to this rcpm\n",
> +                                       ws->name);

IMO printing this message is not useful in general, because it looks
like you just want to skip wakeup sources that aren't associated with
rcpm devices.

Maybe use pr_debug() to print it?  Or maybe use pr_debug() to print a
message if you have found a suitable device?  Wouldn't that be more
useful?

> +                       continue;
> +               }
> +

It would be good to add a comment explaining what the code below does
here.  Or explain that in the function's kerneldoc comment.

> +               for (i = 0; i < rcpm->wakeup_cells; i++) {

It looks like 'tmp' can be defined in this block.

And I would store the value of value[i+1] in tmp upfront, that is

u32 tmp = value[i+1];

> +                       /* We can only OR related bits */
> +                       if (value[i + 1]) {

Also I would do

if (!tmp)
        continue;

to reduce the indentation level.

> +                               if (rcpm->little_endian) {
> +                                       tmp = ioread32(base + i * 4);
> +                                       tmp |= value[i + 1];
> +                                       iowrite32(tmp, base + i * 4);

So it is sufficient to do

tmp |= ioread32(base + i * 4);
iowrite32(tmp, base + i * 4);

here and analogously below.

You may as well define

void __iomem *address = base + i * 4;

and use it everywhere in this block instead of the (base + I * 4) expression.

> +                               } else {
> +                                       tmp = ioread32be(base + i * 4);
> +                                       tmp |= value[i + 1];
> +                                       iowrite32be(tmp, base + i * 4);
> +                               }
> +                       }
> +               }
> +       }
> +
> +       wakeup_sources_read_unlock(idx);
> +
> +       return 0;
> +}
> +
> +static const struct dev_pm_ops rcpm_pm_ops = {
> +       .prepare =  rcpm_pm_prepare,
> +};
> +