Message-Id: <20120517210633.400633E0621@localhost>
Date:	Thu, 17 May 2012 15:06:33 -0600
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
	x86@...nel.org
Cc:	Jerome Oufella <jerome.oufella@...oirfairelinux.com>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	lm-sensors@...sensors.org,
	Guenter Roeck <guenter.roeck@...csson.com>,
	Jean Delvare <khali@...ux-fr.org>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
Subject: Re: [PATCH v6 3/3] gpio: TS-5500 GPIO support

On Thu, 12 Apr 2012 20:28:55 -0400, Vivien Didelot <vivien.didelot@...oirfairelinux.com> wrote:
> From: Jerome Oufella <jerome.oufella@...oirfairelinux.com>
> 
> Signed-off-by: Jerome Oufella <jerome.oufella@...oirfairelinux.com>
> Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>
> ---
>  MAINTAINERS                   |    2 +
>  arch/x86/include/asm/ts5500.h |   62 ++++++++

Why the separate header file?  What will use these defines?  I
normally expect driver-specific defines to be in the driver .c file
directly; particularly for things like gpio drivers which should be a
generic interface that doesn't need to export symbols.

>  drivers/gpio/Kconfig          |    7 +
>  drivers/gpio/Makefile         |    1 +
>  drivers/gpio/gpio-ts5500.c    |  347 +++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 419 insertions(+)
>  create mode 100644 arch/x86/include/asm/ts5500.h
>  create mode 100644 drivers/gpio/gpio-ts5500.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b126129..b7b5d95 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6624,6 +6624,8 @@ TECHNOLOGIC SYSTEMS TS-5500 MACHINE SUPPORT
>  M:	Savoir-faire Linux Inc. <kernel@...oirfairelinux.com>
>  S:	Maintained
>  F:	arch/x86/platform/ts5500/
> +F:	arch/x86/include/asm/ts5500.h
> +F:	drivers/gpio/gpio-ts5500.c
>  
>  TEGRA SUPPORT
>  M:	Colin Cross <ccross@...roid.com>
> diff --git a/arch/x86/include/asm/ts5500.h b/arch/x86/include/asm/ts5500.h
> new file mode 100644
> index 0000000..baf136c
> --- /dev/null
> +++ b/arch/x86/include/asm/ts5500.h
> @@ -0,0 +1,62 @@
> +/*
> + * Technologic Systems TS-5500 GPIO (DIO) definitions
> + *
> + * Copyright (c) 2010-2012 Savoir-faire Linux Inc.
> + *	Jerome Oufella <jerome.oufella@...oirfairelinux.com>
> + *
> + * 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.
> + */
> +
> +#ifndef _TS5500_H
> +#define _TS5500_H
> +
> +#define TS5500_DIO1_0		0
> +#define TS5500_DIO1_1		1
> +#define TS5500_DIO1_2		2
> +#define TS5500_DIO1_3		3
> +#define TS5500_DIO1_4		4
> +#define TS5500_DIO1_5		5
> +#define TS5500_DIO1_6		6
> +#define TS5500_DIO1_7		7
> +#define TS5500_DIO1_8		8
> +#define TS5500_DIO1_9		9
> +#define TS5500_DIO1_10		10
> +#define TS5500_DIO1_11		11
> +#define TS5500_DIO1_12		12
> +#define TS5500_DIO1_13		13
> +
> +#define TS5500_DIO2_0		14
> +#define TS5500_DIO2_1		15
> +#define TS5500_DIO2_2		16
> +#define TS5500_DIO2_3		17
> +#define TS5500_DIO2_4		18
> +#define TS5500_DIO2_5		19
> +#define TS5500_DIO2_6		20
> +#define TS5500_DIO2_7		21
> +#define TS5500_DIO2_8		22
> +#define TS5500_DIO2_9		23
> +#define TS5500_DIO2_10		24
> +#define TS5500_DIO2_11		25
> +/* #define TS5500_DIO2_12 - Keep commented out as it simply doesn't exist. */
> +#define TS5500_DIO2_13		26
> +
> +#define TS5500_LCD_0		27
> +#define TS5500_LCD_1		28
> +#define TS5500_LCD_2		29
> +#define TS5500_LCD_3		30
> +#define TS5500_LCD_4		31
> +#define TS5500_LCD_5		32
> +#define TS5500_LCD_6		33
> +#define TS5500_LCD_7		34
> +#define TS5500_LCD_EN		35
> +#define TS5500_LCD_RS		36
> +#define TS5500_LCD_WR		37
> +
> +/* Lines that can trigger IRQs */
> +#define TS5500_DIO1_13_IRQ	7
> +#define TS5500_DIO2_13_IRQ	6
> +#define TS5500_LCD_RS_IRQ	1
> +
> +#endif /* _TS5500_H */
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index edadbda..a19b0f3 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -319,6 +319,13 @@ config GPIO_TPS65912
>  	help
>  	  This driver supports TPS65912 gpio chip
>  
> +config GPIO_TS5500
> +	tristate "TS-5500 GPIOs"
> +	depends on TS5500
> +	help
> +	  This driver supports the DIO headers for GPIO usage on the Technologic
> +	  Systems TS-5500 platform.
> +
>  config GPIO_TWL4030
>  	tristate "TWL4030, TWL5030, and TPS659x0 GPIOs"
>  	depends on TWL4030_CORE
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 007f54b..30cbd03 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -56,6 +56,7 @@ obj-$(CONFIG_GPIO_TIMBERDALE)	+= gpio-timberdale.o
>  obj-$(CONFIG_ARCH_DAVINCI_TNETV107X) += gpio-tnetv107x.o
>  obj-$(CONFIG_GPIO_TPS65910)	+= gpio-tps65910.o
>  obj-$(CONFIG_GPIO_TPS65912)	+= gpio-tps65912.o
> +obj-$(CONFIG_GPIO_TS5500)	+= gpio-ts5500.o
>  obj-$(CONFIG_GPIO_TWL4030)	+= gpio-twl4030.o
>  obj-$(CONFIG_GPIO_UCB1400)	+= gpio-ucb1400.o
>  obj-$(CONFIG_GPIO_VR41XX)	+= gpio-vr41xx.o
> diff --git a/drivers/gpio/gpio-ts5500.c b/drivers/gpio/gpio-ts5500.c
> new file mode 100644
> index 0000000..01f34d8
> --- /dev/null
> +++ b/drivers/gpio/gpio-ts5500.c
> @@ -0,0 +1,347 @@
> +/*
> + * GPIO (DIO) driver for Technologic Systems TS-5500
> + *
> + * TS-5500 board has 38 GPIOs referred to as DIOs in the product's literature.
> + *
> + * Copyright (c) 2010-2012 Savoir-faire Linux Inc.
> + *	Jerome Oufella <jerome.oufella@...oirfairelinux.com>
> + *	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
> + *
> + * 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.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/gpio.h>
> +#include <linux/io.h>
> +#include <linux/platform_device.h>
> +#include <asm/ts5500.h>
> +
> +static int dio1_irq = 1;
> +module_param(dio1_irq, int, 0644);
> +MODULE_PARM_DESC(dio1_irq, "Enable usage of IRQ7 for any DIO1 line"
> +		 " (default 1)");
> +
> +static int dio2_irq;
> +module_param(dio2_irq, int, 0644);
> +MODULE_PARM_DESC(dio2_irq, "Enable usage of IRQ6 for any DIO2 line"
> +		 " (default 0)");
> +
> +static int lcd_irq;
> +module_param(lcd_irq, int, 0644);
> +MODULE_PARM_DESC(lcd_irq, "Enable usage of IRQ1 for any LCD line"
> +		 " (default 0)");
> +
> +static int use_lcdio;
> +module_param(use_lcdio, int, 0644);
> +MODULE_PARM_DESC(use_lcdio, "Enable usage of the LCD header for DIO operation"
> +		 " (default 0)");
> +
> +static DEFINE_SPINLOCK(gpio_lock);
> +
> +static inline void port_bit_set(u8 addr, int bit)
> +{
> +	u8 var;
> +
> +	var = inb(addr);
> +	var |= (1 << bit);
> +	outb(var, addr);
> +}
> +
> +static inline void port_bit_clear(u8 addr, int bit)
> +{
> +	u8 var;
> +
> +	var = inb(addr);
> +	var &= ~(1 << bit);
> +	outb(var, addr);
> +}
> +
> +/* "DIO" line to IO port mapping table for line's value */
> +static const unsigned long line_to_port_map[] = {
> +	0x7B, 0x7B, 0x7B, 0x7B, 0x7B, 0x7B, 0x7B, 0x7B,	/* DIO1_[0-7] */
> +	0x7C, 0x7C, 0x7C, 0x7C, 0x7C, 0x7C,		/* DIO1_[8-13] */
> +	0x7E, 0x7E, 0x7E, 0x7E, 0x7E, 0x7E, 0x7E, 0x7E,	/* DIO2_[0-7] */
> +	0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F,		/* DIO2_[8-13] */
> +	0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,	/* LCD_[0-7] */
> +	0x73, 0x73, 0x73				/* LCD_{EN,RS,WR} */
> +};
> +
> +/* "DIO" line to IO port's bit map for line's value */
> +static const int line_to_bit_map[] = {
> +	0, 1, 2, 3, 4, 5, 6, 7,	/* DIO1_[0-7] */
> +	0, 1, 2, 3, 4, 5,	/* DIO1_[8-13] */
> +	0, 1, 2, 3, 4, 5, 6, 7,	/* DIO2_[0-7] */
> +	0, 1, 2, 3, 4, 5,	/* DIO2_[8-13] */
> +	0, 1, 2, 3, 4, 5, 6, 7,	/* LCD_[0-7] */
> +	0, 7, 6			/* LCD_{EN,RS,WR} */
> +};
> +
> +/* "DIO" line's direction control mapping table */
> +static const unsigned long line_to_dir_map[] = {
> +	0x7A, 0x7A, 0x7A, 0x7A, 0x7A, 0x7A, 0x7A, 0x7A,	/* DIO1_[0-7] */
> +	0x7A, 0x7A, 0x7A, 0x7A, 0, 0,			/* DIO1_[8-13] */
> +	0x7D, 0x7D, 0x7D, 0x7D, 0x7D, 0x7D, 0x7D, 0x7D,	/* DIO2_[0-7] */
> +	0x7D, 0x7D, 0x7D, 0x7D, 0, 0,			/* DIO2_[8-13] */
> +	0x7D, 0x7D, 0x7D, 0x7D, 0x7D, 0x7D, 0x7D, 0x7D,	/* LCD_[0-7] */
> +	0, 0, 0						/* LCD_{EN,RS,WR} */
> +};
> +
> +/* "DIO" line's direction control bit-mapping table */
> +static const int line_to_dir_bit_map[] = {
> +	0, 0, 0, 0, 1, 1, 1, 1,	/* DIO1_[0-7] */
> +	5, 5, 5, 5, -1, -1,	/* DIO1_[8-13] */
> +	0, 0, 0, 0, 1, 1, 1, 1,	/* DIO2_[0-7] */
> +	5, 5, 5, 5, -1, -1,	/* DIO2_[8-13] */
> +	2, 2, 2, 2, 3, 3, 3, 3,	/* LCD_[0-7] */
> +	-1, -1, -1		/* LCD_{EN,RS,WR} */
> +};

Splitting up this data into 4 arrays seems odd.  I think it would be
better to define a single table with a tuple for each line.

> +
> +static int ts5500_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
> +{
> +	unsigned long dir_reg, flags;
> +	int dir_bit;
> +
> +	/* Some lines cannot be configured as input */
> +	if (offset == TS5500_LCD_EN)
> +		return -ENXIO;
> +
> +	dir_reg = line_to_dir_map[offset];
> +	dir_bit = line_to_dir_bit_map[offset];
> +
> +	spin_lock_irqsave(&gpio_lock, flags);
> +	port_bit_clear(dir_reg, dir_bit);
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +
> +	return 0;
> +}
> +
> +static int ts5500_gpio_get(struct gpio_chip *chip, unsigned offset)
> +{
> +	unsigned long ioaddr;
> +	int bitno;
> +
> +	ioaddr = line_to_port_map[offset];
> +	bitno = line_to_bit_map[offset];
> +
> +	return (inb(ioaddr) >> bitno) & 0x1;
> +}
> +
> +static int ts5500_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
> +					int val)
> +{
> +	unsigned long dir_reg, ioaddr, flags;
> +	int dir_bit, bitno;
> +
> +	/* Some lines cannot be configured as output */
> +	switch (offset) {
> +	case TS5500_DIO1_12:
> +	case TS5500_DIO1_13:
> +	case TS5500_DIO2_13:
> +	case TS5500_LCD_RS:
> +	case TS5500_LCD_WR:
> +		return -ENXIO;

This would also do well in a 'flags' field in the per-line data table
as I described above.

> +	default:
> +		break;
> +	}
> +
> +	dir_reg = line_to_dir_map[offset];
> +	dir_bit = line_to_dir_bit_map[offset];
> +	ioaddr = line_to_port_map[offset];
> +	bitno = line_to_bit_map[offset];
> +
> +	spin_lock_irqsave(&gpio_lock, flags);
> +	port_bit_set(dir_reg, dir_bit);
> +	if (val)
> +		port_bit_set(ioaddr, bitno);
> +	else
> +		port_bit_clear(ioaddr, bitno);
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +
> +	return 0;
> +}
> +
> +static void ts5500_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
> +{
> +	int bitno;
> +	unsigned long ioaddr, flags;
> +
> +	ioaddr = line_to_port_map[offset];
> +	bitno = line_to_bit_map[offset];
> +
> +	spin_lock_irqsave(&gpio_lock, flags);
> +	if (val)
> +		port_bit_set(ioaddr, bitno);
> +	else
> +		port_bit_clear(ioaddr, bitno);
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +}
> +
> +static int ts5500_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
> +{
> +	/* Only a few lines are IRQ-capable */
> +	if (offset == TS5500_DIO1_13)
> +		return TS5500_DIO1_13_IRQ;
> +	if (offset == TS5500_DIO2_13)
> +		return TS5500_DIO2_13_IRQ;
> +	if (offset == TS5500_LCD_RS)
> +		return TS5500_LCD_RS_IRQ;
> +
> +	/* IRQ line may be bridged with another DIO line from the same header */
> +	if (dio1_irq && offset >= TS5500_DIO1_0 && offset < TS5500_DIO1_13)
> +		return TS5500_DIO1_13_IRQ;
> +	if (dio2_irq && offset >= TS5500_DIO2_0 && offset < TS5500_DIO2_13)
> +		return TS5500_DIO2_13_IRQ;
> +	if (lcd_irq && offset >= TS5500_LCD_0 && offset <= TS5500_LCD_WR)
> +		return TS5500_LCD_RS_IRQ;

Also candidate for putting in the table.

> +
> +	return -ENXIO;
> +}
> +
> +static struct gpio_chip ts5500_gpio_chip = {
> +	.label = "ts5500-gpio",
> +	.owner = THIS_MODULE,
> +	.direction_input = ts5500_gpio_direction_input,
> +	.get = ts5500_gpio_get,
> +	.direction_output = ts5500_gpio_direction_output,
> +	.set = ts5500_gpio_set,
> +	.to_irq = ts5500_gpio_to_irq,
> +	.base = TS5500_DIO1_0,

Don't hard code the GPIO base.  It should be dynamically assigned by
using '-1' here.

> +};
> +
> +static void ts5500_gpio_release(struct device *dev)
> +{
> +	/* noop */
> +}
> +
> +static struct platform_device ts5500_gpio_pdev = {
> +	.name = "ts5500-gpio",
> +	.id = -1,
> +	.dev = {
> +		.release = ts5500_gpio_release,
> +	},
> +};
> +
> +static int __devinit ts5500_gpio_probe(struct platform_device *pdev)
> +{
> +	int ret;
> +	unsigned long flags;
> +
> +	if (pdev == NULL)
> +		return -ENODEV;
> +
> +	if (!request_region(0x7A, 3, "ts5500-gpio-DIO1")) {
> +		dev_err(&pdev->dev, "failed to request I/O port 0x7A-7C\n");
> +		return -EBUSY;
> +	}
> +
> +	if (!request_region(0x7D, 3, "ts5500-gpio-DIO2")) {
> +		dev_err(&pdev->dev, "failed to request I/O port 0x7D-7F\n");
> +		ret = -EBUSY;
> +		goto release_dio1;
> +	}
> +
> +	if (use_lcdio && !request_region(0x72, 2, "ts5500-gpio-LCD")) {
> +		dev_err(&pdev->dev, "failed to request I/O port 0x72-73\n");
> +		ret = -EBUSY;
> +		goto release_dio2;
> +	}
> +
> +	if (use_lcdio)
> +		ts5500_gpio_chip.ngpio = TS5500_LCD_WR + 1;
> +	else
> +		ts5500_gpio_chip.ngpio = TS5500_DIO2_13 + 1;
> +
> +	ret = gpiochip_add(&ts5500_gpio_chip);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to register the gpio chip\n");
> +		goto release_lcd;
> +	}
> +
> +	/* Enable IRQ generation */
> +	spin_lock_irqsave(&gpio_lock, flags);
> +	port_bit_set(0x7A, 7); /* DIO1_13 on IRQ7 */
> +	port_bit_set(0x7D, 7); /* DIO2_13 on IRQ6 */
> +	if (use_lcdio) {
> +		port_bit_clear(0x7D, 4); /* LCD header usage as DIO */
> +		port_bit_set(0x7D, 6); /* LCD_RS on IRQ1 */
> +	}
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +
> +	return 0;
> +
> +release_lcd:
> +	if (use_lcdio)
> +		release_region(0x72, 2);
> +release_dio2:
> +	release_region(0x7D, 3);
> +release_dio1:
> +	release_region(0x7A, 3);
> +
> +	return ret;
> +}
> +
> +static int __devexit ts5500_gpio_remove(struct platform_device *pdev)
> +{
> +	int ret;
> +	unsigned long flags;
> +
> +	/* Disable IRQ generation */
> +	spin_lock_irqsave(&gpio_lock, flags);
> +	port_bit_clear(0x7A, 7);
> +	port_bit_clear(0x7D, 7);
> +	if (use_lcdio)
> +		port_bit_clear(0x7D, 6);
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +
> +	release_region(0x7A, 3);
> +	release_region(0x7D, 3);
> +	if (use_lcdio)
> +		release_region(0x72, 2);
> +
> +	ret = gpiochip_remove(&ts5500_gpio_chip);
> +	if (ret)
> +		dev_err(&pdev->dev, "failed to remove the gpio chip\n");
> +
> +	return ret;
> +}
> +
> +static struct platform_driver ts5500_gpio_driver = {
> +	.driver = {
> +		.name = "ts5500-gpio",
> +		.owner = THIS_MODULE,
> +	},
> +	.probe = ts5500_gpio_probe,
> +	.remove = __devexit_p(ts5500_gpio_remove),
> +};
> +
> +static int __init ts5500_gpio_init(void)
> +{
> +	int ret;
> +
> +	ret = platform_driver_register(&ts5500_gpio_driver);
> +	if (ret)
> +		return ret;
> +
> +	ret = platform_device_register(&ts5500_gpio_pdev);
> +	if (ret) {
> +		platform_driver_unregister(&ts5500_gpio_driver);
> +		return ret;
> +	}

As already discussed....  Bleah!!  :-)

Please move the device registration to platform setup code.

> +
> +	return 0;
> +}
> +module_init(ts5500_gpio_init);
> +
> +static void __exit ts5500_gpio_exit(void)
> +{
> +	platform_driver_unregister(&ts5500_gpio_driver);
> +	platform_device_unregister(&ts5500_gpio_pdev);
> +}
> +module_exit(ts5500_gpio_exit);

module_platform_driver() will replace some of the boilerplate.

g.
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