Re: [PATCH v14 1/5] mfd: mxs-lradc: Add support for mxs-lradc MFD

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Wed, Mar 01, 2017 at 09:10:50PM +0100, Stefan Wahren wrote:
> > Ksenija Stanojevic <ksenija.stanojevic@gmail.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@gmail.com>
> > Acked-by: Lee Jones <lee.jones@linaro.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@gmail.com>
> > + *
> > + * Authors:
> > + *  Marek Vasut <marex@denx.de>
> > + *  Ksenija Stanojevic <ksenija.stanojevic@gmail.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?

I am not Lee, but given that this module already parses touchscreen
properties and knows whether there is touchscreen or not, #1 seems
simple and logical.

Thanks.

-- 
Dmitry