Message-ID: <300114e2-6794-db3c-a51c-3f900b6476f9@collabora.com>
Date:   Fri, 4 Mar 2022 11:31:38 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Mattijs Korpershoek <mkorpershoek@...libre.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Marco Felsch <m.felsch@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Fengping Yu <fengping.yu@...iatek.com>,
        Yingjoe Chen <yingjoe.chen@...iatek.com>
Cc:     Fabien Parent <fparent@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v21 2/3] Input: mt6779-keypad - Add MediaTek keypad driver

Il 03/03/22 16:43, Mattijs Korpershoek ha scritto:
> From: "fengping.yu" <fengping.yu@...iatek.com>
> 
> This patch adds matrix keypad support for Mediatek SoCs.
> 
> Signed-off-by: fengping.yu <fengping.yu@...iatek.com>
> Reviewed-by: Marco Felsch <m.felsch@...gutronix.de>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Reviewed-by: Mattijs Korpershoek <mkorpershoek@...libre.com>
> Signed-off-by: Mattijs Korpershoek <mkorpershoek@...libre.com>

Hello Mattijs,
thanks for the patch!

However, to make it perfect, there's something to improve....

> ---
>   drivers/input/keyboard/Kconfig         |  12 ++
>   drivers/input/keyboard/Makefile        |   1 +
>   drivers/input/keyboard/mt6779-keypad.c | 215 +++++++++++++++++++++++++
>   3 files changed, 228 insertions(+)
>   create mode 100644 drivers/input/keyboard/mt6779-keypad.c
> 
> diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
> index 0c607da9ee10..03a9530f620e 100644
> --- a/drivers/input/keyboard/Kconfig
> +++ b/drivers/input/keyboard/Kconfig
> @@ -779,6 +779,18 @@ config KEYBOARD_BCM
>   	  To compile this driver as a module, choose M here: the
>   	  module will be called bcm-keypad.
>   
> +config KEYBOARD_MT6779
> +	tristate "MediaTek Keypad Support"
> +	depends on ARCH_MEDIATEK || COMPILE_TEST
> +	select REGMAP_MMIO
> +	select INPUT_MATRIXKMAP
> +	help
> +	  Say Y here if you want to use the keypad on MediaTek SoCs.
> +	  If unsure, say N.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called mt6779-keypad.
> +
>   config KEYBOARD_MTK_PMIC
>   	tristate "MediaTek PMIC keys support"
>   	depends on MFD_MT6397
> diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
> index e3c8648f834e..721936e90290 100644
> --- a/drivers/input/keyboard/Makefile
> +++ b/drivers/input/keyboard/Makefile
> @@ -44,6 +44,7 @@ obj-$(CONFIG_KEYBOARD_MATRIX)		+= matrix_keypad.o
>   obj-$(CONFIG_KEYBOARD_MAX7359)		+= max7359_keypad.o
>   obj-$(CONFIG_KEYBOARD_MCS)		+= mcs_touchkey.o
>   obj-$(CONFIG_KEYBOARD_MPR121)		+= mpr121_touchkey.o
> +obj-$(CONFIG_KEYBOARD_MT6779)		+= mt6779-keypad.o
>   obj-$(CONFIG_KEYBOARD_MTK_PMIC) 	+= mtk-pmic-keys.o
>   obj-$(CONFIG_KEYBOARD_NEWTON)		+= newtonkbd.o
>   obj-$(CONFIG_KEYBOARD_NOMADIK)		+= nomadik-ske-keypad.o
> diff --git a/drivers/input/keyboard/mt6779-keypad.c b/drivers/input/keyboard/mt6779-keypad.c
> new file mode 100644
> index 000000000000..b207acdd1e2a
> --- /dev/null
> +++ b/drivers/input/keyboard/mt6779-keypad.c
> @@ -0,0 +1,215 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2022 MediaTek Inc.
> + * Author Fengping Yu <fengping.yu@...iatek.com>
> + */
> +#include <linux/bitops.h>
> +#include <linux/clk.h>
> +#include <linux/input/matrix_keypad.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#define MTK_KPD_NAME		"mt6779-keypad"
> +#define MTK_KPD_MEM		0x0004
> +#define MTK_KPD_DEBOUNCE	0x0018
> +#define MTK_KPD_DEBOUNCE_MASK	GENMASK(13, 0)
> +#define MTK_KPD_DEBOUNCE_MAX_MS	256
> +#define MTK_KPD_NUM_MEMS	5
> +#define MTK_KPD_NUM_BITS	136	/* 4*32+8 MEM5 only use 8 BITS */
> +
> +struct mt6779_keypad {
> +	struct regmap *regmap;
> +	struct input_dev *input_dev;
> +	struct clk *clk;
> +	void __iomem *base;
> +	u32 n_rows;
> +	u32 n_cols;
> +	DECLARE_BITMAP(keymap_state, MTK_KPD_NUM_BITS);
> +};
> +
> +static const struct regmap_config mt6779_keypad_regmap_cfg = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = sizeof(u32),
> +	.max_register = 36,

Are you sure that you can't use .fast_io = true?

Another version for the same question:
Are you sure that you need to lock with a mutex here, and not with a spinlock?

Since you're performing reads over a MMIO, I think that there's a very good
chance that you can use fast_io.

> +};
> +
> +static irqreturn_t mt6779_keypad_irq_handler(int irq, void *dev_id)
> +{
> +	struct mt6779_keypad *keypad = dev_id;
> +	unsigned short *keycode = keypad->input_dev->keycode;
> +	DECLARE_BITMAP(new_state, MTK_KPD_NUM_BITS);
> +	DECLARE_BITMAP(change, MTK_KPD_NUM_BITS);
> +	int bit_nr;
> +	int pressed;
> +	unsigned short code;
> +	int row, col;
> +	int row_shift = get_count_order(keypad->n_cols);
> +
> +	regmap_bulk_read(keypad->regmap, MTK_KPD_MEM,
> +			 new_state, MTK_KPD_NUM_MEMS);
> +
> +	bitmap_xor(change, new_state, keypad->keymap_state, MTK_KPD_NUM_BITS);
> +
> +	for_each_set_bit(bit_nr, change, MTK_KPD_NUM_BITS) {
> +	/* For 32bits register, only bits [15:0] use to indicate key status */
> +		if (bit_nr % 32 >= 16)
> +			continue;
> +
> +		/* 1: not pressed, 0: pressed */
> +		pressed = !test_bit(bit_nr, new_state);
> +		dev_dbg(&keypad->input_dev->dev, "%s",
> +			pressed ? "pressed" : "released");
> +
> +		row = bit_nr / 32;
> +		col = bit_nr % 32;
> +
> +		code = keycode[MATRIX_SCAN_CODE(row, col, row_shift)];
> +
> +		input_report_key(keypad->input_dev, code, pressed);
> +		input_sync(keypad->input_dev);
> +
> +		dev_dbg(&keypad->input_dev->dev,
> +			"report Linux keycode = %d\n", code);
> +	}
> +
> +	bitmap_copy(keypad->keymap_state, new_state, MTK_KPD_NUM_BITS);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void mt6779_keypad_clk_disable(void *data)
> +{
> +	clk_disable_unprepare(data);
> +}
> +
> +static int mt6779_keypad_pdrv_probe(struct platform_device *pdev)
> +{
> +	struct mt6779_keypad *keypad;
> +	unsigned int irq;
> +	u32 debounce;
> +	bool wakeup;
> +	int error;
> +
> +	keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
> +	if (!keypad)
> +		return -ENOMEM;
> +
> +	keypad->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(keypad->base))
> +		return PTR_ERR(keypad->base);
> +
> +	keypad->regmap = devm_regmap_init_mmio(&pdev->dev,
> +					       keypad->base,
> +					       &mt6779_keypad_regmap_cfg);

Please use dev_err_probe() to simplify error handling in probe functions: you've
done a great job with adding a devm action for the error cases, avoiding gotos to
get out cleanly.. it would be a pity to not finish this to perfection.

I'll give you two examples for this, so that you'll be all set.

	if (IS_ERR(keypad->regmap))
		return dev_err_probe(&pdev->dev, PTR_ERR(keypad->regmap),
				     "regmap init failed\n");

P.S.: No need for %pe here, as dev_err_probe prints the error number for you!

> +	if (IS_ERR(keypad->regmap)) {
> +		dev_err(&pdev->dev,
> +			"regmap init failed:%pe\n", keypad->regmap);
> +		return PTR_ERR(keypad->regmap);
> +	}
> +
> +	bitmap_fill(keypad->keymap_state, MTK_KPD_NUM_BITS);
> +
> +	keypad->input_dev = devm_input_allocate_device(&pdev->dev);

	if (!keypad->input_dev)
		return dev_err_probe(&pdev->dev, -ENOMEM,
				     "Cannot allocate input device\n");

> +	if (!keypad->input_dev) {
> +		dev_err(&pdev->dev, "Failed to allocate input dev\n");
> +		return -ENOMEM;
> +	}
> +
> +	keypad->input_dev->name = MTK_KPD_NAME;
> +	keypad->input_dev->id.bustype = BUS_HOST;
> +
> +	error = matrix_keypad_parse_properties(&pdev->dev, &keypad->n_rows,
> +					       &keypad->n_cols);
> +	if (error) {
> +		dev_err(&pdev->dev, "Failed to parse keypad params\n");
> +		return error;
> +	}
> +
> +	if (device_property_read_u32(&pdev->dev, "debounce-delay-ms",
> +				     &debounce))
> +		debounce = 16;
> +
> +	if (debounce > MTK_KPD_DEBOUNCE_MAX_MS) {
> +		dev_err(&pdev->dev, "Debounce time exceeds the maximum allowed time %dms\n",
> +			MTK_KPD_DEBOUNCE_MAX_MS);
> +		return -EINVAL;
> +	}
> +
> +	wakeup = device_property_read_bool(&pdev->dev, "wakeup-source");
> +
> +	dev_dbg(&pdev->dev, "n_row=%d n_col=%d debounce=%d\n",
> +		keypad->n_rows, keypad->n_cols, debounce);
> +
> +	error = matrix_keypad_build_keymap(NULL, NULL,
> +					   keypad->n_rows,
> +					   keypad->n_cols,
> +					   NULL,
> +					   keypad->input_dev);
> +	if (error) {
> +		dev_err(&pdev->dev, "Failed to build keymap\n");
> +		return error;
> +	}
> +
> +	regmap_write(keypad->regmap, MTK_KPD_DEBOUNCE,
> +		     (debounce * (1 << 5)) & MTK_KPD_DEBOUNCE_MASK);
> +
> +	keypad->clk = devm_clk_get(&pdev->dev, "kpd");
> +	if (IS_ERR(keypad->clk))
> +		return PTR_ERR(keypad->clk);
> +
> +	error = clk_prepare_enable(keypad->clk);
> +	if (error) {
> +		dev_err(&pdev->dev, "cannot prepare/enable keypad clock\n");
> +		return error;
> +	}
> +
> +	error = devm_add_action_or_reset(&pdev->dev, mt6779_keypad_clk_disable, keypad->clk);
> +	if (error)
> +		return error;
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return irq;
> +
> +	error = devm_request_threaded_irq(&pdev->dev, irq, NULL, mt6779_keypad_irq_handler,
> +					  IRQF_ONESHOT, MTK_KPD_NAME, keypad);
> +	if (error) {
> +		dev_err(&pdev->dev, "Failed to request IRQ#%d:%d\n", irq, error);
> +		return error;
> +	}
> +
> +	error = input_register_device(keypad->input_dev);
> +	if (error) {
> +		dev_err(&pdev->dev, "Failed to register device\n");
> +		return error;
> +	}
> +
> +	error =  device_init_wakeup(&pdev->dev, wakeup);

Whoops! Two spaces here! Please fix this typo.

P.S.: Please add my email to the Cc's when you'll send the next version, so that
       I will be able to timely give you a R-b tag.

Cheers,
Angelo

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