Message-ID: <282870591.38324.1488399050890@email.1und1.de>
Date:   Wed, 1 Mar 2017 21:10:50 +0100 (CET)
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     Ksenija Stanojevic <ksenija.stanojevic@...il.com>,
        lee.jones@...aro.org
Cc:     linux-input@...r.kernel.org, pmeerw@...erw.net, jic23@...nel.org,
        knaack.h@....de, lars@...afoo.de, dmitry.torokhov@...il.com,
        harald@...ib.org, linux-kernel@...r.kernel.org,
        fabio.estevam@...escale.com, linux-iio@...r.kernel.org,
        marex@...x.de
Subject: Re: [PATCH v14 1/5] mfd: mxs-lradc: Add support for mxs-lradc MFD

> Ksenija Stanojevic <ksenija.stanojevic@...il.com> hat am 1. März 2017 um 19:02 geschrieben:
> 
> 
> Add core files for low resolution analog-to-digital converter (mxs-lradc)
> MFD driver.
> 
> Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@...il.com>
> Acked-by: Lee Jones <lee.jones@...aro.org>
> ---
> Changes in v14:
>  - none
> 
> Changes in v13:
>  - none
> 
> Changes in v12:
>  - use BIT macro
> 
> Changes in v11:
>  - create static struct mfd_cells
>  - don't set platform data in mfd cells, set driver data instead
>  - remove mxs_lradc_reg_* functions, use writel function instead
> 
> Changes in v10:
>  - fetch base address from DT
>  - add a NULL check for of_match_device
> 
> Changes in v9:
>  - improve commit message.
> 
> Changes in v8:
>  - rebase onto 4.9-rc1
> 
> Changes in v7:
>  - define macros ADC_CELL and TSC_CELL
>  - remove one cell and dynamically set them in the switch()
>  - fail in the touchscreen driver instead of mfd driver if
>    hardware doesn't contain a touchscreen
> 
> Changes in v6:
>  - update copyright
>  - add kernel-doc header for struct mxs-lradc
>  - add error message
>  - change EINVAL to ENODEV
>  - use PLATFORM_DEVID_NONE instead -1
>  - cosmetic fixes
> 
> Changes in v5:
>  - use DEFINE_RES_MEM
>  - don't pass ioreammaped adress to platform cells
>  - move comment outside of struct mxs_lradc
>  - change type of argument in mxs_lradc_reg_set, mxs_lradc_reg_clear,
>    mxs_lradc_reg_wrt (struct mxs_lradc * -> void __iomem *)
> 
> Changes in v4:
>  - update copyright
>  - use DEFINE_RES_IRQ_NAMED
>  - remove mxs_lradc_add_device function
>  - use struct mfd_cell in static form
>  - improve spacing
>  - remove unnecessary comment
>  - remove platform_get_irq
>  - remove touch_ret and use ret instead
>  - rename use_touchscreen to touchscreen_wire
>  - use goto statements
>  - remove irq[13], irq_count and irq_name from struct mxs_lradc
>  - remove all defines from inside the struct definition
> 
> Changes in v3:
>  - add note to commit message
>  - move switch statement into if(touch_ret == 0) branch
>  - add MODULE_AUTHOR
> 
> Changes in v2:
>  - do not change spacing in Kconfig
>  - make struct mfd_cell part of struct mxs_lradc
>  - use switch instead of if in mxs_lradc_irq_mask
>  - use only necessary header files in mxs_lradc.h
>  - use devm_mfd_add_device
>  - use separate function to register mfd device
>  - change licence to GPL
>  - add copyright
> 
>  drivers/mfd/Kconfig           |  17 +++
>  drivers/mfd/Makefile          |   1 +
>  drivers/mfd/mxs-lradc.c       | 264 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/mxs-lradc.h | 187 ++++++++++++++++++++++++++++++
>  4 files changed, 469 insertions(+)
>  create mode 100644 drivers/mfd/mxs-lradc.c
>  create mode 100644 include/linux/mfd/mxs-lradc.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 55ecdfb..8bbc91b 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -344,6 +344,23 @@ config MFD_MC13XXX_I2C
>  	help
>  	  Select this if your MC13xxx is connected via an I2C bus.
>  
> +config MFD_MXS_LRADC
> +	tristate "Freescale i.MX23/i.MX28 LRADC"
> +	depends on ARCH_MXS || COMPILE_TEST
> +	select MFD_CORE
> +	select STMP_DEVICE
> +	help
> +	  Say yes here to build support for the Low Resolution
> +	  Analog-to-Digital Converter (LRADC) found on the i.MX23 and i.MX28
> +	  processors. This driver provides common support for accessing the
> +	  device, additional drivers must be enabled in order to use the
> +	  functionality of the device:
> +		mxs-lradc-adc for ADC readings
> +		mxs-lradc-ts  for touchscreen support
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called mxs-lradc.
> +
>  config MFD_MX25_TSADC
>  	tristate "Freescale i.MX25 integrated Touchscreen and ADC unit"
>  	select REGMAP_MMIO
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 31ce076..790698a 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -215,3 +215,4 @@ obj-$(CONFIG_MFD_ALTERA_A10SR)	+= altera-a10sr.o
>  obj-$(CONFIG_MFD_SUN4I_GPADC)	+= sun4i-gpadc.o
>  
>  obj-$(CONFIG_MFD_STM32_TIMERS) 	+= stm32-timers.o
> +obj-$(CONFIG_MFD_MXS_LRADC)     += mxs-lradc.o
> diff --git a/drivers/mfd/mxs-lradc.c b/drivers/mfd/mxs-lradc.c
> new file mode 100644
> index 0000000..2ae8487
> --- /dev/null
> +++ b/drivers/mfd/mxs-lradc.c
> @@ -0,0 +1,264 @@
> +/*
> + * Freescale MXS Low Resolution Analog-to-Digital Converter driver
> + *
> + * Copyright (c) 2012 DENX Software Engineering, GmbH.
> + * Copyright (c) 2017 Ksenija Stanojevic <ksenija.stanojevic@...il.com>
> + *
> + * Authors:
> + *  Marek Vasut <marex@...x.de>
> + *  Ksenija Stanojevic <ksenija.stanojevic@...il.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/mxs-lradc.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define ADC_CELL		0
> +#define TSC_CELL		1
> +#define RES_MEM			0
> +
> +enum mx23_lradc_irqs {
> +	MX23_LRADC_TS_IRQ = 0,
> +	MX23_LRADC_CH0_IRQ,
> +	MX23_LRADC_CH1_IRQ,
> +	MX23_LRADC_CH2_IRQ,
> +	MX23_LRADC_CH3_IRQ,
> +	MX23_LRADC_CH4_IRQ,
> +	MX23_LRADC_CH5_IRQ,
> +	MX23_LRADC_CH6_IRQ,
> +	MX23_LRADC_CH7_IRQ,
> +};
> +
> +enum mx28_lradc_irqs {
> +	MX28_LRADC_TS_IRQ = 0,
> +	MX28_LRADC_TRESH0_IRQ,
> +	MX28_LRADC_TRESH1_IRQ,
> +	MX28_LRADC_CH0_IRQ,
> +	MX28_LRADC_CH1_IRQ,
> +	MX28_LRADC_CH2_IRQ,
> +	MX28_LRADC_CH3_IRQ,
> +	MX28_LRADC_CH4_IRQ,
> +	MX28_LRADC_CH5_IRQ,
> +	MX28_LRADC_CH6_IRQ,
> +	MX28_LRADC_CH7_IRQ,
> +	MX28_LRADC_BUTTON0_IRQ,
> +	MX28_LRADC_BUTTON1_IRQ,
> +};
> +
> +static struct resource mx23_adc_resources[] = {
> +	DEFINE_RES_MEM(0x0, 0x0),
> +	DEFINE_RES_IRQ_NAMED(MX23_LRADC_CH0_IRQ, "mxs-lradc-channel0"),
> +	DEFINE_RES_IRQ_NAMED(MX23_LRADC_CH1_IRQ, "mxs-lradc-channel1"),
> +	DEFINE_RES_IRQ_NAMED(MX23_LRADC_CH2_IRQ, "mxs-lradc-channel2"),
> +	DEFINE_RES_IRQ_NAMED(MX23_LRADC_CH3_IRQ, "mxs-lradc-channel3"),
> +	DEFINE_RES_IRQ_NAMED(MX23_LRADC_CH4_IRQ, "mxs-lradc-channel4"),
> +	DEFINE_RES_IRQ_NAMED(MX23_LRADC_CH5_IRQ, "mxs-lradc-channel5"),
> +};
> +
> +static struct resource mx23_touchscreen_resources[] = {
> +	DEFINE_RES_MEM(0x0, 0x0),
> +	DEFINE_RES_IRQ_NAMED(MX23_LRADC_TS_IRQ, "mxs-lradc-touchscreen"),
> +	DEFINE_RES_IRQ_NAMED(MX23_LRADC_CH6_IRQ, "mxs-lradc-channel6"),
> +	DEFINE_RES_IRQ_NAMED(MX23_LRADC_CH7_IRQ, "mxs-lradc-channel7"),
> +};
> +
> +static struct resource mx28_adc_resources[] = {
> +	DEFINE_RES_MEM(0x0, 0x0),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_TRESH0_IRQ, "mxs-lradc-thresh0"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_TRESH1_IRQ, "mxs-lradc-thresh1"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_CH0_IRQ, "mxs-lradc-channel0"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_CH1_IRQ, "mxs-lradc-channel1"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_CH2_IRQ, "mxs-lradc-channel2"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_CH3_IRQ, "mxs-lradc-channel3"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_CH4_IRQ, "mxs-lradc-channel4"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_CH5_IRQ, "mxs-lradc-channel5"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_BUTTON0_IRQ, "mxs-lradc-button0"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_BUTTON1_IRQ, "mxs-lradc-button1"),
> +};
> +
> +static struct resource mx28_touchscreen_resources[] = {
> +	DEFINE_RES_MEM(0x0, 0x0),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_TS_IRQ, "mxs-lradc-touchscreen"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_CH6_IRQ, "mxs-lradc-channel6"),
> +	DEFINE_RES_IRQ_NAMED(MX28_LRADC_CH7_IRQ, "mxs-lradc-channel7"),
> +};
> +
> +static struct mfd_cell mx23_cells[] = {
> +	{
> +		.name = "mxs-lradc-adc",
> +		.resources = mx23_adc_resources,
> +		.num_resources = ARRAY_SIZE(mx23_adc_resources),
> +	},
> +	{
> +		.name = "mxs-lradc-ts",
> +		.resources = mx23_touchscreen_resources,
> +		.num_resources = ARRAY_SIZE(mx23_touchscreen_resources),
> +	},
> +};
> +
> +static struct mfd_cell mx28_cells[] = {
> +	{
> +		.name = "mxs-lradc-adc",
> +		.resources = mx28_adc_resources,
> +		.num_resources = ARRAY_SIZE(mx28_adc_resources),
> +	},
> +	{
> +		.name = "mxs-lradc-ts",
> +		.resources = mx28_touchscreen_resources,
> +		.num_resources = ARRAY_SIZE(mx28_touchscreen_resources),
> +	}
> +};
> +
> +static const struct of_device_id mxs_lradc_dt_ids[] = {
> +	{ .compatible = "fsl,imx23-lradc", .data = (void *)IMX23_LRADC, },
> +	{ .compatible = "fsl,imx28-lradc", .data = (void *)IMX28_LRADC, },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, mxs_lradc_dt_ids);
> +
> +static int mxs_lradc_probe(struct platform_device *pdev)
> +{
> +	const struct of_device_id *of_id;
> +	struct device *dev = &pdev->dev;
> +	struct device_node *node = dev->of_node;
> +	struct mxs_lradc *lradc;
> +	struct mfd_cell *cells = NULL;
> +	struct resource *res;
> +	int ret = 0;
> +	u32 ts_wires = 0;
> +
> +	lradc = devm_kzalloc(&pdev->dev, sizeof(*lradc), GFP_KERNEL);
> +	if (!lradc)
> +		return -ENOMEM;
> +
> +	of_id = of_match_device(mxs_lradc_dt_ids, &pdev->dev);
> +	if (!of_id)
> +		return -EINVAL;
> +
> +	lradc->soc = (enum mxs_lradc_id)of_id->data;
> +
> +	lradc->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(lradc->clk)) {
> +		dev_err(dev, "Failed to get the delay unit clock\n");
> +		return PTR_ERR(lradc->clk);
> +	}
> +
> +	ret = clk_prepare_enable(lradc->clk);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable the delay unit clock\n");
> +		return ret;
> +	}
> +
> +	ret = of_property_read_u32(node, "fsl,lradc-touchscreen-wires",
> +					 &ts_wires);
> +
> +	if (!ret) {
> +		lradc->buffer_vchans = BUFFER_VCHANS_LIMITED;
> +
> +		switch (ts_wires) {
> +		case 4:
> +			lradc->touchscreen_wire = MXS_LRADC_TOUCHSCREEN_4WIRE;
> +			break;
> +		case 5:
> +			if (lradc->soc == IMX28_LRADC) {
> +				lradc->touchscreen_wire =
> +					MXS_LRADC_TOUCHSCREEN_5WIRE;
> +				break;
> +			}
> +			/* fall through to an error message for i.MX23 */
> +		default:
> +			dev_err(&pdev->dev,
> +				"Unsupported number of touchscreen wires (%d)\n"
> +				, ts_wires);
> +			ret = -EINVAL;
> +			goto err_clk;
> +		}
> +	} else {
> +		lradc->buffer_vchans = BUFFER_VCHANS_ALL;
> +	}
> +
> +	platform_set_drvdata(pdev, lradc);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENOMEM;
> +
> +	switch (lradc->soc) {
> +	case IMX23_LRADC:
> +		mx23_adc_resources[RES_MEM] = *res;
> +		mx23_touchscreen_resources[RES_MEM] = *res;
> +		cells = mx23_cells;
> +		break;
> +	case IMX28_LRADC:
> +		mx28_adc_resources[RES_MEM] = *res;
> +		mx28_touchscreen_resources[RES_MEM] = *res;
> +		cells = mx28_cells;
> +		break;
> +	default:
> +		dev_err(dev, "Unsupported SoC\n");
> +		ret = -ENODEV;
> +		goto err_clk;
> +	}
> +
> +	ret = devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
> +				   &cells[ADC_CELL], 1, NULL, 0, NULL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to add the ADC subdevice\n");
> +		goto err_clk;
> +	}
> +
> +	ret = devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
> +				   &cells[TSC_CELL], 1, NULL, 0, NULL);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"Failed to add the touchscreen subdevice\n");
> +		goto err_clk;
> +	}

Since touchscreen is optional it doesn't make to try to register it, notice in the touchscreen driver there is no touchscreen, give the user a confusing error and finally disable the clock.

Here are my suggestions:

1) Use the solution from Patch V6 but with an explaining comment that touchscreen is optional

if (!lradc->touchscreen_wire)
	return 0;

2) Return a special error from touchscreen registration so mfd knowns this result is expected.

I'm open for better solutions.

@Lee: What's your opinion?

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