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    SubjectRe: [PATCH 2/2] clk: max77620: Add clock driver for MAX77620/MAX20024
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    Hello Laxman,

    On Fri, Jun 10, 2016 at 6:12 AM, Laxman Dewangan <ldewangan@nvidia.com> wrote:
    > MAXIM MAX77620 is the power management IC with multiple DCDC/LDO(
    > regulators, RTC, GPIOs, Watchdog, 32KHz clock source etc.
    >
    > Add support for controlling the 32KHz clock source via clock
    > framework.
    >
    > Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
    > ---

    It looks very similar to the max77686 and max77802 drivers (with only
    the difference in number of clock outputs), can you use the helpers in
    drivers/clk/clk-max-gen.c ?

    > drivers/clk/Kconfig | 9 +++
    > drivers/clk/Makefile | 1 +
    > drivers/clk/clk-max77620.c | 143 +++++++++++++++++++++++++++++++++++++++++++++
    > 3 files changed, 153 insertions(+)
    > create mode 100644 drivers/clk/clk-max77620.c
    >
    > diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
    > index 98efbfc..149f813 100644
    > --- a/drivers/clk/Kconfig
    > +++ b/drivers/clk/Kconfig
    > @@ -34,6 +34,15 @@ source "drivers/clk/versatile/Kconfig"
    > config COMMON_CLK_MAX_GEN
    > bool
    >
    > +config COMMON_CLK_MAX77620
    > + tristate "Clock driver for Maxim 77620/MAX20024 MFD"
    > + depends on MFD_MAX77620
    > + ---help---
    > + This driver supports Maxim MAX77620/MAX20024 32KHz crystal
    > + oscillator. These multi-function devices have one fixed rate.
    > + The clock can be ON and OFF. Say y to make this driver as
    > + built-in and m to make it as module.
    > +
    > config COMMON_CLK_MAX77686
    > tristate "Clock driver for Maxim 77686 MFD"
    > depends on MFD_MAX77686
    > diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
    > index dcc5e69..8c2de43 100644
    > --- a/drivers/clk/Makefile
    > +++ b/drivers/clk/Makefile
    > @@ -26,6 +26,7 @@ obj-$(CONFIG_ARCH_CLPS711X) += clk-clps711x.o
    > obj-$(CONFIG_ARCH_EFM32) += clk-efm32gg.o
    > obj-$(CONFIG_ARCH_HIGHBANK) += clk-highbank.o
    > obj-$(CONFIG_MACH_LOONGSON32) += clk-ls1x.o
    > +obj-$(CONFIG_COMMON_CLK_MAX77620) += clk-max77620.o
    > obj-$(CONFIG_COMMON_CLK_MAX_GEN) += clk-max-gen.o
    > obj-$(CONFIG_COMMON_CLK_MAX77686) += clk-max77686.o
    > obj-$(CONFIG_COMMON_CLK_MAX77802) += clk-max77802.o
    > diff --git a/drivers/clk/clk-max77620.c b/drivers/clk/clk-max77620.c
    > new file mode 100644
    > index 0000000..615cf2e
    > --- /dev/null
    > +++ b/drivers/clk/clk-max77620.c
    > @@ -0,0 +1,143 @@
    > +/*
    > + * Clock driver for Maxim Max77620 device.
    > + *
    > + * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
    > + *
    > + * This program is free software; you can redistribute it and/or modify it
    > + * under the terms and conditions of the GNU General Public License,
    > + * version 2, as published by the Free Software Foundation.
    > + */
    > +
    > +#include <linux/clk.h>
    > +#include <linux/clkdev.h>
    > +#include <linux/clk-provider.h>
    > +#include <linux/mfd/max77620.h>
    > +#include <linux/module.h>
    > +#include <linux/of.h>
    > +#include <linux/platform_device.h>
    > +#include <linux/regmap.h>
    > +#include <linux/slab.h>
    > +
    > +struct max77620_clks_info {
    > + struct device *dev;
    > + struct regmap *rmap;
    > + struct clk *clk;
    > + struct clk_hw hw;
    > +};
    > +
    > +static struct max77620_clks_info *to_max77620_clks_info(struct clk_hw *hw)
    > +{
    > + return container_of(hw, struct max77620_clks_info, hw);
    > +}
    > +
    > +static unsigned long max77620_clks_recalc_rate(struct clk_hw *hw,
    > + unsigned long parent_rate)
    > +{
    > + return 32768;
    > +}
    > +
    > +static int max77620_clks_prepare(struct clk_hw *hw)
    > +{
    > + struct max77620_clks_info *mci = to_max77620_clks_info(hw);
    > +
    > + return regmap_update_bits(mci->rmap, MAX77620_REG_CNFG1_32K,
    > + MAX77620_CNFG1_32K_OUT0_EN,
    > + MAX77620_CNFG1_32K_OUT0_EN);
    > +}
    > +
    > +static void max77620_clks_unprepare(struct clk_hw *hw)
    > +{
    > + struct max77620_clks_info *mci = to_max77620_clks_info(hw);
    > +
    > + regmap_update_bits(mci->rmap, MAX77620_REG_CNFG1_32K,
    > + MAX77620_CNFG1_32K_OUT0_EN, 0);
    > +}
    > +
    > +static int max77620_clks_is_prepared(struct clk_hw *hw)
    > +{
    > + struct max77620_clks_info *mci = to_max77620_clks_info(hw);
    > + unsigned int rval;
    > + int ret;
    > +
    > + ret = regmap_read(mci->rmap, MAX77620_REG_CNFG1_32K, &rval);
    > + if (ret < 0)
    > + return ret;
    > +
    > + return !!(rval & MAX77620_CNFG1_32K_OUT0_EN);
    > +}
    > +
    > +static struct clk_ops max77620_clks_ops = {
    > + .prepare = max77620_clks_prepare,
    > + .unprepare = max77620_clks_unprepare,
    > + .is_prepared = max77620_clks_is_prepared,
    > + .recalc_rate = max77620_clks_recalc_rate,
    > +};
    > +
    > +struct clk_init_data max77620_clk_init_data = {
    > + .name = "clk-32k",
    > + .ops = &max77620_clks_ops,
    > + .flags = CLK_IGNORE_UNUSED,
    > +};
    > +

    Is really needed to ignore this clock if unused? Consumers should
    define this clock and enable if needed.

    > +static int max77620_clks_probe(struct platform_device *pdev)
    > +{
    > + struct device_node *np = pdev->dev.parent->of_node;
    > + struct max77620_clks_info *mci;
    > + struct clk *clk;
    > + int ret;
    > +
    > + mci = devm_kzalloc(&pdev->dev, sizeof(*mci), GFP_KERNEL);
    > + if (!mci)
    > + return -ENOMEM;
    > +
    > + platform_set_drvdata(pdev, mci);
    > +
    > + mci->dev = &pdev->dev;
    > + mci->rmap = dev_get_regmap(pdev->dev.parent, NULL);
    > + if (!mci->rmap) {
    > + dev_err(mci->dev, "Failed to get parent regmap\n");
    > + return -ENODEV;
    > + }
    > + mci->hw.init = &max77620_clk_init_data;
    > +
    > + clk = devm_clk_register(&pdev->dev, &mci->hw);
    > + if (IS_ERR(clk)) {
    > + ret = PTR_ERR(clk);
    > + dev_err(mci->dev, "Fail to register clock: %d\n", ret);
    > + return ret;
    > + }
    > +
    > + mci->clk = clk;
    > + ret = of_clk_add_provider(np, of_clk_src_simple_get, mci->clk);
    > + if (ret < 0)
    > + dev_err(&pdev->dev, "Fail to add clock driver, %d\n", ret);
    > +
    > + return ret;
    > +}
    > +
    > +static int max77620_clks_remove(struct platform_device *pdev)
    > +{
    > + of_clk_del_provider(pdev->dev.parent->of_node);
    > +
    > + return 0;
    > +}
    > +
    > +static struct platform_device_id max77620_clks_devtype[] = {
    > + { .name = "max77620-clock", },
    > + {},
    > +};
    > +

    Your Kconfig symbol is tristate so the driver can be built as a module
    but autoload will not work because the driver is not exporting a
    module alias.

    IOW, you need MODULE_DEVICE_TABLE(platform, max77620_clks_devtype) here.

    > +static struct platform_driver max77620_clks_driver = {
    > + .driver = {
    > + .name = "max77620-clock",
    > + },
    > + .probe = max77620_clks_probe,
    > + .remove = max77620_clks_remove,
    > + .id_table = max77620_clks_devtype,
    > +};
    > +
    > +module_platform_driver(max77620_clks_driver);
    > +
    > +MODULE_DESCRIPTION("Clock driver for Maxim max77620 PMIC Device");
    > +MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
    > +MODULE_LICENSE("GPL v2");
    > --
    > 2.1.4
    >
    > --
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