Date:	Sun, 29 Jun 2008 21:47:52 +0200
From:	Michael Buesch <mb@...sch.de>
To:	"linux-kernel" <linux-kernel@...r.kernel.org>
Subject: Drivers for selfmade hardware

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");

-- 
Greetings Michael.
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