Re: [PATCH 05/12] mfd: mtk-audsys: add MediaTek audio subsystem driver

Lee Jones
2018-01-02T16:31:03Z

On Tue, 02 Jan 2018, Ryder Lee wrote:

> Add a common driver for the top block of the MediaTek audio subsystem.
> This is a wrapper which manages resources for audio components.
>
> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
> ---
> drivers/mfd/Kconfig | 9 ++++
> drivers/mfd/Makefile | 2 +
> drivers/mfd/mtk-audsys.c | 138 +++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 149 insertions(+)
> create mode 100644 drivers/mfd/mtk-audsys.c
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 1d20a80..ea50b51 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -368,6 +368,15 @@ config MFD_MC13XXX_I2C
> help
> Select this if your MC13xxx is connected via an I2C bus.
>
> +config MFD_MEDIATEK_AUDSYS
> + tristate "MediaTek audio subsystem interface"
> + select MDF_CORE
> + select REGMAP_MMIO
> + help
> + Select this if you have a audio subsystem in MediaTek SoC.
> + The audio subsystem has at least a clock driver part and some
> + audio components.
> +
> config MFD_MXS_LRADC
> tristate "Freescale i.MX23/i.MX28 LRADC"
> depends on ARCH_MXS || COMPILE_TEST
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index d9474ad..3e20927 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -101,6 +101,8 @@ obj-$(CONFIG_MFD_MC13XXX) += mc13xxx-core.o
> obj-$(CONFIG_MFD_MC13XXX_SPI) += mc13xxx-spi.o
> obj-$(CONFIG_MFD_MC13XXX_I2C) += mc13xxx-i2c.o
>
> +obj-$(CONFIG_MFD_MEDIATEK_AUDSYS) += mtk-audsys.o
> +
> obj-$(CONFIG_MFD_CORE) += mfd-core.o
>
> obj-$(CONFIG_EZX_PCAP) += ezx-pcap.o
> diff --git a/drivers/mfd/mtk-audsys.c b/drivers/mfd/mtk-audsys.c
> new file mode 100644
> index 0000000..89399e1
> --- /dev/null
> +++ b/drivers/mfd/mtk-audsys.c
> @@ -0,0 +1,138 @@
> +/*
> + * Mediatek audio subsystem core driver
> + *
> + * Copyright (c) 2017 MediaTek Inc.
> + *
> + * Author: Ryder Lee <ryder.lee@mediatek.com>
> + *
> + * For licencing details see kernel-base/COPYING

You can't do that.

Grep for SPDX to see what is expected.

> + *
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#define AUDSYS_MAX_CLK_NUM 3

When is this not 3?

> +struct sys_dev {
> + struct device *dev;
> + struct regmap *regmap;
> + int clk_num;
> + struct clk *clks[];
> +};
> +
> +static const struct regmap_config aud_regmap_config = {
> + .reg_bits = 32,
> + .reg_stride = 4,
> + .val_bits = 32,
> + .max_register = 0x15e0,
> + .cache_type = REGCACHE_NONE,
> +};
> +
> +static int mtk_subsys_enable(struct sys_dev *sys)
> +{
> + struct device *dev = sys->dev;

I would remove dev and regmap from the sys_dev struct and pass in pdev
directly into this function. Then use platform_get_drvdata() as you
did in .remove().

> + struct clk *clk;
> + int i, ret;
> +
> + for (i = 0; i < sys->clk_num; i++) {
> + clk = of_clk_get(dev->of_node, i);
> + if (IS_ERR(clk)) {
> + if (PTR_ERR(clk) == -EPROBE_DEFER)
> + return -EPROBE_DEFER;
> + break;
> + }
> + sys->clks[i] = clk;
> + }
> +
> + for (i = 0; i < sys->clk_num && sys->clks[i]; i++) {

Why do you need a separate loop for this?

Just prepare and enable valid clocks in the for() loop above.

> + ret = clk_prepare_enable(sys->clks[i]);
> + if (ret)
> + goto err_enable_clks;
> + }
> +
> + return 0;
> +
> +err_enable_clks:
> + while (--i >= 0)
> + clk_disable_unprepare(sys->clks[i]);
> +
> + return ret;
> +}
> +
> +static int mtk_subsys_probe(struct platform_device *pdev)
> +{
> + struct sys_dev *sys;
> + struct resource *res;
> + void __iomem *mmio;
> + int num, ret;
> +
> + num = (int)of_device_get_match_data(&pdev->dev);
> + if (!num)
> + return -EINVAL;

This is a very rigid method of achieving your aim. Please find a way
to make this more dynamic. You're probably better off counting the
elements within the property, checking to ensure there aren't more
than the maximum pre-allocated/allowed clocks, then using the number
gleaned directly from the Device Tree.

> + sys = devm_kzalloc(&pdev->dev, sizeof(*sys) +
> + sizeof(struct clk *) * num, GFP_KERNEL);

You need to add bracketing here for clarity.

> + if (!sys)
> + return -ENOMEM;
> +
> + sys->clk_num = num;
> + sys->dev = &pdev->dev;

Why are you saving the device pointer?

> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + mmio = devm_ioremap_resource(sys->dev, res);
> + if (IS_ERR(mmio))
> + return PTR_ERR(mmio);
> +
> + sys->regmap = devm_regmap_init_mmio(sys->dev, mmio,
> + &aud_regmap_config);

Why are you saving a devm'ed regmap pointer?

> + if (IS_ERR(sys->regmap))
> + return PTR_ERR(sys->regmap);
> +
> + platform_set_drvdata(pdev, sys);
> +
> + /* Enable top level clocks */
> + ret = mtk_subsys_enable(sys);

mtk_subsys_enable_clks()

> + if (ret)
> + return ret;
> +
> + return devm_of_platform_populate(sys->dev);
> +};
> +
> +static int mtk_subsys_remove(struct platform_device *pdev)
> +{
> + struct sys_dev *sys = platform_get_drvdata(pdev);
> + int i;
> +
> + for (i = sys->clk_num - 1; i >= 0; i--)
> + if (sys->clks[i])

This check is superfluous as the clk subsystem does this for you.

> + clk_disable_unprepare(sys->clks[i]);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id of_match_audsys[] = {
> + {
> + .compatible = "mediatek,mt2701-audsys-core",
> + .data = (void *)AUDSYS_MAX_CLK_NUM,

You can remove this line.

> + },
> + {},
> +};
> +MODULE_DEVICE_TABLE(platform, of_match_audsys);
> +
> +static struct platform_driver audsys_drv = {
> + .probe = mtk_subsys_probe,
> + .remove = mtk_subsys_remove,
> + .driver = {
> + .name = "mediatek-audsys-core",
> + .of_match_table = of_match_ptr(of_match_audsys),
> + },
> +};
> +
> +builtin_platform_driver(audsys_drv);
> +
> +MODULE_DESCRIPTION("Mediatek audio subsystem core driver");

> +MODULE_LICENSE("GPL");

<just_checking>
Are you sure this is what you want?
</just_checking>

--
Lee Jones
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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