Date:	Sun, 29 Jun 2008 22:26:16 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Michael Buesch <mb@...sch.de>
Cc:	"linux-kernel" <linux-kernel@...r.kernel.org>
Subject: Re: Drivers for selfmade hardware

On Sun, 29 Jun 2008 21:47:52 +0200
Michael Buesch <mb@...sch.de> wrote:

> I'm wondering what the policy is for selfmade hardware
> or other hardware where only a few pieces exist. Is it desired
> to get drivers for this kind of hardware merged upstream into the
> mainline kernel?
> 
> I have a tiny driver that can be used to drive a modified
> Brooktree 8xx based card in 24-port GPIO mode.
> So the card can be used as a cheap digital PCI GPIO card.
> This hardware can be built with some soldering skills, a tiny
> soldering tip and a few hours of free time.
> 
> So what's the policy? Push to mainline or keep as seperate
> patch?
> 
> (The following patch is not complete, but just what I have for now
> to show you...)
> 
> Index: linux-2.6/drivers/gpio/Kconfig
> ===================================================================
> --- linux-2.6.orig/drivers/gpio/Kconfig	2008-05-01 13:19:48.000000000 +0200
> +++ linux-2.6/drivers/gpio/Kconfig	2008-06-29 21:19:26.000000000 +0200
> @@ -61,6 +61,24 @@ config GPIO_PCF857X
>  	  This driver provides an in-kernel interface to those GPIOs using
>  	  platform-neutral GPIO calls.
>  
> +comment "PCI GPIO expanders:"
> +
> +config GPIO_BT8XX
> +	tristate "BT8XX GPIO abuser"
> +	depends on PCI && !VIDEO_BT848
> +	help
> +	  The BT8xx frame grabber chip has 24 GPIO pins than can be abused
> +	  as a cheap PCI GPIO card.
> +
> +	  This chip can be found on Miro, Hauppauge and STB TV-cards.
> +
> +	  The card needs to be physically altered for using it as a
> +	  GPIO card. For more information on how to build a GPIO card
> +	  from a BT8xx TV card, see the following link:
> +	  http://bu3sch.de/btgpio.php
> +
> +	  If unsure, say N.
> +
>  comment "SPI GPIO expanders:"
>  
>  config GPIO_MCP23S08
> Index: linux-2.6/drivers/gpio/Makefile
> ===================================================================
> --- linux-2.6.orig/drivers/gpio/Makefile	2008-05-01 13:19:48.000000000 +0200
> +++ linux-2.6/drivers/gpio/Makefile	2008-06-29 17:58:05.000000000 +0200
> @@ -7,3 +7,4 @@ obj-$(CONFIG_HAVE_GPIO_LIB)	+= gpiolib.o
>  obj-$(CONFIG_GPIO_MCP23S08)	+= mcp23s08.o
>  obj-$(CONFIG_GPIO_PCA953X)	+= pca953x.o
>  obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
> +obj-$(CONFIG_GPIO_BT8XX)	+= btgpio.o
> Index: linux-2.6/drivers/gpio/btgpio.c
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ linux-2.6/drivers/gpio/btgpio.c	2008-06-29 19:21:23.000000000 +0200
> @@ -0,0 +1,334 @@
> +/*
> +
> +    bt8xx GPIO abuser
> +
> +    Copyright (C) 2008 Michael Buesch <mb@...sch.de>
> +
> +    Please do _only_ contact Michael Buesch with issues related to this driver.
> +    All the other people listed below are not related to this driver. Their names
> +    are only here, because this driver is derived from the bt848 driver.
> +
> +
> +    Derived from the bt848 driver:
> +
> +    Copyright (C) 1996,97,98 Ralph  Metzler
> +			   & Marcus Metzler
> +    (c) 1999-2002 Gerd Knorr
> +
> +    some v4l2 code lines are taken from Justin's bttv2 driver which is
> +    (c) 2000 Justin Schoeman
> +
> +    V4L1 removal from:
> +    (c) 2005-2006 Nickolay V. Shmyrev
> +
> +    Fixes to be fully V4L2 compliant by
> +    (c) 2006 Mauro Carvalho Chehab
> +
> +    Cropping and overscan support
> +    Copyright (C) 2005, 2006 Michael H. Schimek
> +    Sponsored by OPQ Systems AB
> +
> +    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.
> +
> +    You should have received a copy of the GNU General Public License
> +    along with this program; if not, write to the Free Software
> +    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> +*/
> +
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/spinlock.h>
> +#include <asm/gpio.h>
> +
> +/* Steal the hardware definitions from the bttv driver. */
> +#include "../media/video/bt8xx/bt848.h"
> +
> +
> +struct btgpio {
> +	spinlock_t lock;
> +
> +	void __iomem *mmio;
> +	struct pci_dev *pdev;
> +	struct gpio_chip gpio;
> +
> +#ifdef CONFIG_PM
> +	u32 saved_outen;
> +	u32 saved_data;
> +#endif
> +};
> +
> +#define bgwrite(dat,adr)    writel((dat), bg->mmio+(adr))
> +#define bgread(adr)         readl(bg->mmio+(adr))
> +
> +
> +static int btgpio_gpio_direction_input(struct gpio_chip *gpio, unsigned nr)
> +{
> +	struct btgpio *bg = container_of(gpio, struct btgpio, gpio);
> +	unsigned long flags;
> +	u32 outen, data;
> +
> +	spin_lock_irqsave(&bg->lock, flags);
> +
> +	data = bgread(BT848_GPIO_DATA);
> +	data &= ~(1 << nr);
> +	bgwrite(data, BT848_GPIO_DATA);
> +
> +	outen = bgread(BT848_GPIO_OUT_EN);
> +	outen &= ~(1 << nr);
> +	bgwrite(outen, BT848_GPIO_OUT_EN);
> +
> +	spin_unlock_irqrestore(&bg->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int btgpio_gpio_get(struct gpio_chip *gpio, unsigned nr)
> +{
> +	struct btgpio *bg = container_of(gpio, struct btgpio, gpio);
> +	unsigned long flags;
> +	u32 val;
> +
> +	spin_lock_irqsave(&bg->lock, flags);
> +	val = bgread(BT848_GPIO_DATA);
> +	spin_unlock_irqrestore(&bg->lock, flags);
> +
> +	return !!(val & (1 << nr));
> +}
> +
> +static int btgpio_gpio_direction_output(struct gpio_chip *gpio,
> +					unsigned nr, int val)
> +{
> +	struct btgpio *bg = container_of(gpio, struct btgpio, gpio);
> +	unsigned long flags;
> +	u32 outen, data;
> +
> +	spin_lock_irqsave(&bg->lock, flags);
> +
> +	data = bgread(BT848_GPIO_DATA);
> +	if (val)
> +		data |= (1 << nr);
> +	else
> +		data &= ~(1 << nr);
> +	bgwrite(data, BT848_GPIO_DATA);
> +
> +	outen = bgread(BT848_GPIO_OUT_EN);
> +	outen |= (1 << nr);
> +	bgwrite(outen, BT848_GPIO_OUT_EN);
> +
> +	spin_unlock_irqrestore(&bg->lock, flags);
> +
> +	return 0;
> +}
> +
> +static void btgpio_gpio_set(struct gpio_chip *gpio,
> +			    unsigned nr, int val)
> +{
> +	struct btgpio *bg = container_of(gpio, struct btgpio, gpio);
> +	unsigned long flags;
> +	u32 data;
> +
> +	spin_lock_irqsave(&bg->lock, flags);
> +
> +	data = bgread(BT848_GPIO_DATA);
> +	if (val)
> +		data |= (1 << nr);
> +	else
> +		data &= ~(1 << nr);
> +	bgwrite(data, BT848_GPIO_DATA);
> +
> +	spin_unlock_irqrestore(&bg->lock, flags);
> +}
> +
> +static void btgpio_gpio_setup(struct btgpio *bg)
> +{
> +	struct gpio_chip *c = &bg->gpio;
> +
> +	c->label = bg->pdev->dev.bus_id;
> +	c->owner = THIS_MODULE;
> +	c->direction_input = btgpio_gpio_direction_input;
> +	c->get = btgpio_gpio_get;
> +	c->direction_output = btgpio_gpio_direction_output;
> +	c->set = btgpio_gpio_set;
> +	c->dbg_show = NULL;
> +	c->base = -1;
> +	c->ngpio = 24;
> +	c->can_sleep = 0;
> +}
> +
> +static int btgpio_probe(struct pci_dev *dev,
> +			const struct pci_device_id *pci_id)
> +{
> +	struct btgpio *bg;
> +	int err;
> +
> +	bg = kzalloc(sizeof(*bg), GFP_KERNEL);
> +	if (!bg)
> +		return -ENOMEM;
> +
> +	bg->pdev = dev;
> +	spin_lock_init(&bg->lock);
> +
> +	err = pci_enable_device(dev);
> +	if (err) {
> +		printk(KERN_ERR "btgpio: Can't enable device.\n");
> +		goto err_freebg;
> +	}
> +	if (!request_mem_region(pci_resource_start(dev, 0),
> +				pci_resource_len(dev, 0),
> +				"btgpio")) {
> +		printk(KERN_WARNING "btgpio: can't request iomem (0x%llx).\n",
> +		       (unsigned long long)pci_resource_start(dev, 0));
> +		err = -EBUSY;
> +		goto err_disable;
> +	}
> +	pci_set_master(dev);
> +	pci_set_drvdata(dev, bg);
> +
> +	bg->mmio = ioremap(pci_resource_start(dev, 0), 0x1000);
> +	if (!bg->mmio) {
> +		printk(KERN_ERR "btgpio: ioremap() failed\n");
> +		err = -EIO;
> +		goto err_release_mem;
> +	}
> +
> +	/* Disable interrupts */
> +	bgwrite(0, BT848_INT_MASK);
> +
> +	/* gpio init */
> +	bgwrite(0, BT848_GPIO_REG_INP);
> +	bgwrite(0, BT848_GPIO_OUT_EN);
> +
> +	btgpio_gpio_setup(bg);
> +	err = gpiochip_add(&bg->gpio);
> +	if (err) {
> +		printk(KERN_ERR "btgpio: Failed to register GPIOs\n");
> +		goto err_release_mem;
> +	}
> +
> +	printk(KERN_INFO "btgpio: Abusing BT8xx card for GPIO\n");
> +
> +	return 0;
> +
> +err_release_mem:
> +	release_mem_region(pci_resource_start(dev, 0),
> +			   pci_resource_len(dev, 0));
> +	pci_set_drvdata(dev, NULL);
> +err_disable:
> +	pci_disable_device(dev);
> +err_freebg:
> +	kfree(bg);
> +
> +	return err;
> +}
> +
> +static void btgpio_remove(struct pci_dev *pdev)
> +{
> +	struct btgpio *bg = pci_get_drvdata(pdev);
> +
> +	gpiochip_remove(&bg->gpio);
> +
> +	bgwrite(0, BT848_INT_MASK);
> +	bgwrite(~0x0, BT848_INT_STAT);
> +	bgwrite(0x0, BT848_GPIO_OUT_EN);
> +
> +	iounmap(bg->mmio);
> +	release_mem_region(pci_resource_start(pdev,0),
> +			   pci_resource_len(pdev,0));
> +	pci_disable_device(pdev);
> +
> +	pci_set_drvdata(pdev, NULL);
> +	kfree(bg);
> +}
> +
> +#ifdef CONFIG_PM
> +static int btgpio_suspend(struct pci_dev *pdev, pm_message_t state)
> +{
> +	struct btgpio *bg = pci_get_drvdata(pdev);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&bg->lock, flags);
> +
> +	bg->saved_outen = bgread(BT848_GPIO_OUT_EN);
> +	bg->saved_data = bgread(BT848_GPIO_DATA);
> +
> +	bgwrite(0, BT848_INT_MASK);
> +	bgwrite(~0x0, BT848_INT_STAT);
> +	bgwrite(0x0, BT848_GPIO_OUT_EN);
> +
> +	spin_unlock_irqrestore(&bg->lock, flags);
> +
> +	pci_save_state(pdev);
> +	pci_disable_device(pdev);
> +	pci_set_power_state(pdev, pci_choose_state(pdev, state));
> +
> +	return 0;
> +}
> +
> +static int btgpio_resume(struct pci_dev *pdev)
> +{
> +	struct btgpio *bg = pci_get_drvdata(pdev);
> +	unsigned long flags;
> +	int err;
> +
> +	pci_set_power_state(pdev, 0);
> +	err = pci_enable_device(pdev);
> +	if (err)
> +		return err;
> +	pci_restore_state(pdev);
> +
> +	spin_lock_irqsave(&bg->lock, flags);
> +
> +	bgwrite(0, BT848_INT_MASK);
> +	bgwrite(0, BT848_GPIO_REG_INP);
> +	bgwrite(bg->saved_outen, BT848_GPIO_OUT_EN);
> +	bgwrite(bg->saved_data, BT848_GPIO_DATA);
> +
> +	spin_unlock_irqrestore(&bg->lock, flags);
> +
> +	return 0;
> +}
> +#endif /* CONFIG_PM */
> +
> +static struct pci_device_id btgpio_pci_tbl[] = {
> +	{ PCI_DEVICE(PCI_VENDOR_ID_BROOKTREE, PCI_DEVICE_ID_BT848) },
> +	{ PCI_DEVICE(PCI_VENDOR_ID_BROOKTREE, PCI_DEVICE_ID_BT849) },
> +	{ PCI_DEVICE(PCI_VENDOR_ID_BROOKTREE, PCI_DEVICE_ID_BT878) },
> +	{ PCI_DEVICE(PCI_VENDOR_ID_BROOKTREE, PCI_DEVICE_ID_BT879) },
> +	{ 0, },
> +};
> +MODULE_DEVICE_TABLE(pci, btgpio_pci_tbl);
> +
> +static struct pci_driver btgpio_pci_driver = {
> +	.name		= "btgpio",
> +	.id_table	= btgpio_pci_tbl,
> +	.probe		= btgpio_probe,
> +	.remove		= btgpio_remove,
> +#ifdef CONFIG_PM
> +	.suspend	= btgpio_suspend,
> +	.resume		= btgpio_resume,
> +#endif
> +};
> +
> +static int btgpio_init(void)
> +{
> +	return pci_register_driver(&btgpio_pci_driver);
> +}
> +module_init(btgpio_init)
> +
> +static void btgpio_exit(void)
> +{
> +	pci_unregister_driver(&btgpio_pci_driver);
> +}
> +module_exit(btgpio_exit)
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Michael Buesch");
> +MODULE_DESCRIPTION("Abuse a BT8xx framegrabber card as generic GPIO card");
> 


-- 
--
	"Alan, I'm getting a bit worried about you."
				-- Linus Torvalds
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