Re: [PATCH v3 2/8] mfd: Add atmel-st driver

[Alexandre Belloni]

Hi Lee,

On 19/01/2015 at 09:42:24 +0000, Lee Jones wrote :
> On Mon, 12 Jan 2015, Alexandre Belloni wrote:
> 
> > The Atmel System Timer IP available on the at91rm9200 exposes both a timer and a
> > watchdog.
> > 
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
> > Acked-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> > ---
> >  drivers/mfd/Kconfig          |  7 ++++
> >  drivers/mfd/Makefile         |  1 +
> >  drivers/mfd/atmel-st.c       | 77 ++++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/mfd/atmel-st.h | 47 +++++++++++++++++++++++++++
> >  4 files changed, 132 insertions(+)
> >  create mode 100644 drivers/mfd/atmel-st.c
> >  create mode 100644 include/linux/mfd/atmel-st.h
> 
> This driver looks pretty pointless.  Why can't you request the sysconf
> registers from within the drivers themselves?
> 

How would you probe the watchdog driver then? Would you had the
"atmel,at91rm9200-st" compatible there?

At some point in time, we should add the reset driver, would you also
match it on "atmel,at91rm9200-st"?

I'm fine with that as this allows to avoid the mfd driver.

> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index 2e6b7311fabc..3c5185c0cf06 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -78,6 +78,13 @@ config MFD_BCM590XX
> >  	help
> >  	  Support for the BCM590xx PMUs from Broadcom
> >  
> > +config MFD_ATMEL_ST
> > +	bool "Atmel System Timer"
> > +	select MFD_CORE
> > +	default SOC_AT91RM9200
> > +	help
> > +	  If you say Y here you get support for the Atmel System Timer.
> > +
> >  config MFD_AXP20X
> >  	bool "X-Powers AXP20X"
> >  	select MFD_CORE
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index 53467e211381..1ecd416f25c5 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -104,6 +104,7 @@ obj-$(CONFIG_PMIC_DA9052)	+= da9052-core.o
> >  obj-$(CONFIG_MFD_DA9052_SPI)	+= da9052-spi.o
> >  obj-$(CONFIG_MFD_DA9052_I2C)	+= da9052-i2c.o
> >  obj-$(CONFIG_MFD_AXP20X)	+= axp20x.o
> > +obj-$(CONFIG_MFD_ATMEL_ST)	+= atmel-st.o
> >  
> >  obj-$(CONFIG_MFD_LP3943)	+= lp3943.o
> >  obj-$(CONFIG_MFD_LP8788)	+= lp8788.o lp8788-irq.o
> > diff --git a/drivers/mfd/atmel-st.c b/drivers/mfd/atmel-st.c
> > new file mode 100644
> > index 000000000000..54106fcfe898
> > --- /dev/null
> > +++ b/drivers/mfd/atmel-st.c
> > @@ -0,0 +1,77 @@
> > +/*
> > + * Copyright (C) 2014 Free Electrons
> > + * Copyright (C) 2014 Atmel
> > + *
> > + * Author: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms of the GNU General Public License version 2 as published by
> > + * the Free Software Foundation.
> > + *
> > + * 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.
> > + *
> > + * You should have received a copy of the GNU General Public License along with
> > + * this program.  If not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#include <linux/mfd/atmel-st.h>
> > +#include <linux/mfd/core.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
> > +
> > +static const struct mfd_cell atmel_st_cells[] = {
> > +	{
> > +		.name = "atmel_st_timer",
> > +	},
> > +	{
> > +		.name = "atmel_st_watchdog",
> > +	},
> > +};
> > +
> > +static int atmel_st_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	struct regmap *regmap_st;
> > +
> > +	regmap_st = syscon_node_to_regmap(dev->of_node);
> > +	if (IS_ERR(regmap_st))
> > +		return PTR_ERR(regmap_st);
> > +	dev_set_drvdata(dev, regmap_st);
> > +
> > +	return mfd_add_devices(dev, -1, atmel_st_cells,
> > +			       ARRAY_SIZE(atmel_st_cells),
> > +			       NULL, 0, NULL);
> > +}
> > +
> > +static int atmel_st_remove(struct platform_device *pdev)
> > +{
> > +	mfd_remove_devices(&pdev->dev);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id atmel_st_match[] = {
> > +	{ .compatible = "atmel,at91rm9200-st" },
> > +	{ /* sentinel */ },
> > +};
> > +
> > +static struct platform_driver atmel_st_driver = {
> > +	.probe = atmel_st_probe,
> > +	.remove = atmel_st_remove,
> > +	.driver = {
> > +		.name = "atmel-system-timer",
> > +		.owner = THIS_MODULE,
> > +		.of_match_table = atmel_st_match,
> > +	},
> > +};
> > +module_platform_driver(atmel_st_driver);
> > +
> > +MODULE_ALIAS("platform:atmel-st");
> > +MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>");
> > +MODULE_DESCRIPTION("Atmel ST (System Timer) driver");
> > +MODULE_LICENSE("GPL");
> > diff --git a/include/linux/mfd/atmel-st.h b/include/linux/mfd/atmel-st.h
> > new file mode 100644
> > index 000000000000..88c6cf8eeb2b
> > --- /dev/null
> > +++ b/include/linux/mfd/atmel-st.h
> > @@ -0,0 +1,47 @@
> > +/*
> > + * Copyright (C) 2005 Ivan Kokshaysky
> > + * Copyright (C) SAN People
> > + *
> > + * System Timer (ST) - System peripherals registers.
> > + * Based on AT91RM9200 datasheet revision E.
> > + *
> > + * 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.
> > + */
> > +
> > +#ifndef __LINUX_MFD_ATMEL_ST_H
> > +#define __LINUX_MFD_ATMEL_ST_H
> > +
> > +#define	AT91_ST_CR		0x00			/* Control Register */
> > +#define 	AT91_ST_WDRST		(1 << 0)		/* Watchdog Timer Restart */
> > +
> > +#define	AT91_ST_PIMR		0x04			/* Period Interval Mode Register */
> > +#define		AT91_ST_PIV		(0xffff <<  0)		/* Period Interval Value */
> > +
> > +#define	AT91_ST_WDMR		0x08			/* Watchdog Mode Register */
> > +#define		AT91_ST_WDV		(0xffff <<  0)		/* Watchdog Counter Value */
> > +#define		AT91_ST_RSTEN		(1	<< 16)		/* Reset Enable */
> > +#define		AT91_ST_EXTEN		(1	<< 17)		/* External Signal Assertion Enable */
> > +
> > +#define	AT91_ST_RTMR		0x0c			/* Real-time Mode Register */
> > +#define		AT91_ST_RTPRES		(0xffff <<  0)		/* Real-time Prescalar Value */
> > +
> > +#define	AT91_ST_SR		0x10			/* Status Register */
> > +#define		AT91_ST_PITS		(1 << 0)		/* Period Interval Timer Status */
> > +#define		AT91_ST_WDOVF		(1 << 1) 		/* Watchdog Overflow */
> > +#define		AT91_ST_RTTINC		(1 << 2) 		/* Real-time Timer Increment */
> > +#define		AT91_ST_ALMS		(1 << 3) 		/* Alarm Status */
> > +
> > +#define	AT91_ST_IER		0x14			/* Interrupt Enable Register */
> > +#define	AT91_ST_IDR		0x18			/* Interrupt Disable Register */
> > +#define	AT91_ST_IMR		0x1c			/* Interrupt Mask Register */
> > +
> > +#define	AT91_ST_RTAR		0x20			/* Real-time Alarm Register */
> > +#define		AT91_ST_ALMV		(0xfffff << 0)		/* Alarm Value */
> > +
> > +#define	AT91_ST_CRTR		0x24			/* Current Real-time Register */
> > +#define		AT91_ST_CRTV		(0xfffff << 0)		/* Current Real-Time Value */
> > +
> > +#endif /* __LINUX_MFD_ATMEL_ST_H */
> 
> -- 
> Lee Jones
> Linaro STMicroelectronics Landing Team Lead
> Linaro.org â Open source software for ARM SoCs
> Follow Linaro: Facebook | Twitter | Blog

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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