Re: [PATCH 2.6.8.1 0/2] leds: new class for led devices
From: Robert Schwebel
Date: Fri Sep 03 2004 - 02:38:02 EST
On Fri, Sep 03, 2004 at 03:17:15PM +0200, Robert Schwebel wrote:
> I'll pull the gpio patch out of my working tree and post it here for
> discussion.
Attached. Parts of it have been taken from your LEDs patch anyway, so it
should be not too difficult to reunify them.
Robert
--
Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
Pengutronix - Linux Solutions for Science and Industry
Handelsregister: Amtsgericht Hildesheim, HRA 2686
Hornemannstraße 12, 31137 Hildesheim, Germany
Phone: +49-5121-28619-0 | Fax: +49-5121-28619-4
Index: kernel/gpio.c
===================================================================
--- a/kernel/gpio.c (revision 0)
+++ b/kernel/gpio.c (revision 205)
@@ -0,0 +1,459 @@
+/*
+ * linux/kernel/gpio.c
+ *
+ * (C) 2004 Robert Schwebel, Pengutronix
+ *
+ * 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/config.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/device.h>
+#include <linux/sysdev.h>
+#include <linux/timer.h>
+#include <linux/proc_fs.h>
+#include <linux/gpio.h>
+
+#define DRIVER_NAME "gpio"
+
+static char mapping[255] = "";
+
+MODULE_AUTHOR("John Lenz, Robert Schwebel");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Generic GPIO Infrastructure");
+module_param_string(mapping, mapping, sizeof(mapping), 0);
+MODULE_PARM_DESC(mapping,
+"period delimited options string to map GPIO pins to userland:\n"
+"\n"
+" <pin>:[out|in][hi|lo]\n"
+"\n"
+" example: mapping=5:out:hi.8:in\n"
+);
+
+static ssize_t gpio_show_level(struct class_device *dev, char *buf);
+static ssize_t gpio_store_level(struct class_device *dev, const char *buf, size_t size);
+static ssize_t gpio_show_policy(struct class_device *dev, char *buf);
+
+struct gpio_properties {
+ unsigned int pin_nr;
+ unsigned char policy; /* GPIO_xxx */
+ char pin_level; /* -1=tristate, 0, 1 */
+ char owner[20];
+ struct gpio_device *gpio_dev;
+};
+
+struct gpio_device {
+ spinlock_t lock; /* protects the props field */
+ struct gpio_properties props;
+ struct class_device class_dev;
+ struct list_head list;
+};
+#define to_gpio_device(d) container_of(d, struct gpio_device, class_dev)
+
+static LIST_HEAD(gpio_list);
+static rwlock_t gpio_list_lock = RW_LOCK_UNLOCKED;
+
+/* gpio_device is static, so we don't have to free it here */
+static void gpio_class_release(struct class_device *dev)
+{
+ return;
+}
+
+static struct class gpio_class = {
+ .name = "gpio",
+ .release = gpio_class_release,
+};
+
+
+/*
+ * Attribute: /sys/class/gpio/gpioX/level
+ */
+static struct class_device_attribute attr_gpio_level = {
+ .attr = { .name = "level", .mode = 0644, .owner = THIS_MODULE },
+ .show = gpio_show_level,
+ .store = gpio_store_level,
+};
+
+static ssize_t gpio_show_level(struct class_device *dev, char *buf)
+{
+ struct gpio_device *gpio_dev = to_gpio_device(dev);
+ ssize_t ret_size = 0;
+
+ if (gpio_dev->props.policy & GPIO_INPUT)
+ gpio_dev->props.pin_level = gpio_get_pin(gpio_dev->props.pin_nr);
+
+ spin_lock(&gpio_dev->lock);
+ ret_size += sprintf(buf, "%i\n", gpio_dev->props.pin_level);
+ spin_unlock(&gpio_dev->lock);
+
+ return ret_size;
+}
+
+static ssize_t gpio_store_level(struct class_device *dev, const char *buf, size_t size)
+{
+ struct gpio_device *gpio_dev = to_gpio_device(dev);
+ long value;
+
+ if (gpio_dev->props.policy & GPIO_INPUT)
+ return -EINVAL;
+
+ value = simple_strtol(buf, NULL, 10);
+ if ((value != 0) && (value != 1))
+ return -EINVAL;
+ gpio_dev->props.pin_level = value;
+
+ /* set real hardware */
+ switch (value) {
+ case 0: gpio_clear_pin(gpio_dev->props.pin_nr);
+ gpio_dir_output(gpio_dev->props.pin_nr);
+ break;
+ case 1: gpio_set_pin(gpio_dev->props.pin_nr);
+ gpio_dir_output(gpio_dev->props.pin_nr);
+ break;
+ default: break;
+ }
+ return size;
+}
+
+/*
+ * Attribute: /sys/class/gpio/gpioX/policy
+ */
+static struct class_device_attribute attr_gpio_policy = {
+ .attr = { .name = "policy", .mode = 0444, .owner = THIS_MODULE },
+ .show = gpio_show_policy,
+ .store = NULL,
+};
+
+static ssize_t gpio_show_policy(struct class_device *dev, char *buf)
+{
+ struct gpio_device *gpio_dev = to_gpio_device(dev);
+ ssize_t ret_size = 0;
+
+ spin_lock(&gpio_dev->lock);
+ if (gpio_dev->props.policy & GPIO_USER)
+ ret_size += sprintf(buf,"userspace\n");
+ if (gpio_dev->props.policy & GPIO_KERNEL)
+ ret_size += sprintf(buf,"kernel\n");
+ spin_unlock(&gpio_dev->lock);
+
+ return ret_size;
+}
+
+static int gpio_read_proc(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ char *p = page;
+ int size = 0;
+ struct gpio_device *gpio_dev;
+ struct list_head *lact, *ltmp;
+
+ if (off != 0)
+ goto end;
+
+ p += sprintf(p, "GPIO POLICY DIRECTION OWNER\n");
+ list_for_each_safe(lact, ltmp, &gpio_list) {
+ gpio_dev = list_entry(lact, struct gpio_device, list);
+ p += sprintf(p, "%3i: ", gpio_dev->props.pin_nr);
+ if (gpio_dev->props.policy & GPIO_KERNEL)
+ p += sprintf(p, "kernel ");
+ if (gpio_dev->props.policy & GPIO_USER)
+ p += sprintf(p, "user space ");
+ if (gpio_dev->props.policy & GPIO_INPUT)
+ p += sprintf(p, "input ");
+ if (gpio_dev->props.policy & GPIO_OUTPUT)
+ p += sprintf(p, "output ");
+ p += sprintf(p, "%s\n", gpio_dev->props.owner);
+ }
+end:
+ size = (p - page);
+ if (size <= off + count)
+ *eof = 1;
+ *start = page + off;
+ size -= off;
+ if (size > count)
+ size = count;
+ if (size < 0)
+ size = 0;
+
+ return size;
+}
+
+/**
+ * request_gpio - register a new object of gpio_device class.
+ *
+ * @pin_nr: GPIO pin which is registered
+ * @owner: name of the driver that owns this pin
+ * @policy: set policy for this pin, which is one of these:
+ * - GPIO_USER or GPIO_KERNEL
+ * - GPIO_INPUT or GPIO_OUTPUT
+ * For user space registered pins a sysfs entry is added.
+ * @init_level: initially configured pin level
+ */
+int request_gpio(unsigned int pin_nr, const char *owner,
+ unsigned char policy, unsigned char init_level)
+{
+ int rc;
+ struct gpio_device *gpio_dev;
+ struct list_head *lact, *ltmp;
+
+ list_for_each_safe(lact, ltmp, &gpio_list) {
+ gpio_dev = list_entry(lact, struct gpio_device, list);
+ if (pin_nr == gpio_dev->props.pin_nr) {
+ printk(KERN_ERR "gpio pin %i is already used by %s\n",
+ pin_nr, gpio_dev->props.owner);
+ return -EBUSY;
+ }
+ }
+
+ /* value checks - FIXME: is there a logical xor in C? */
+ if ( ( (policy & GPIO_USER) && (policy & GPIO_KERNEL)) ||
+ (!(policy & GPIO_USER) && !(policy & GPIO_KERNEL))) {
+ printk(KERN_ERR "%s: policy has to be one of GPIO_KERNEL, GPIO_USER\n", DRIVER_NAME);
+ return -EINVAL;
+ }
+ if ( ( (policy & GPIO_INPUT) && (policy & GPIO_OUTPUT)) ||
+ (!(policy & GPIO_INPUT) && !(policy & GPIO_OUTPUT))) {
+ printk(KERN_ERR "%s: policy has to be one of GPIO_INPUT, GPIO_OUTPUT\n", DRIVER_NAME);
+ return -EINVAL;
+ }
+
+ gpio_dev = kmalloc(sizeof(struct gpio_device), GFP_KERNEL);
+
+ if (unlikely(!gpio_dev)) {
+ printk(KERN_ERR "%s: couldn't allocate memory\n", DRIVER_NAME);
+ return -ENOMEM;
+ }
+
+ spin_lock_init(&gpio_dev->lock);
+ gpio_dev->props.pin_nr = pin_nr;
+ gpio_dev->props.policy = policy;
+ gpio_dev->props.pin_level = init_level;
+ gpio_dev->props.gpio_dev = gpio_dev;
+ strncpy(gpio_dev->props.owner, owner, 20);
+
+ memset(&gpio_dev->class_dev, 0, sizeof(gpio_dev->class_dev));
+ gpio_dev->class_dev.class = &gpio_class;
+ snprintf(gpio_dev->class_dev.class_id, BUS_ID_SIZE, "gpio%i", pin_nr);
+
+ rc = class_device_register(&gpio_dev->class_dev);
+ if (unlikely(rc)) {
+ printk(KERN_ERR "%s: class registering failed\n", DRIVER_NAME);
+ kfree(gpio_dev);
+ return rc;
+ }
+
+ INIT_LIST_HEAD(&gpio_dev->list);
+
+ /* register the attributes */
+ if (policy & GPIO_USER)
+ class_device_create_file(&gpio_dev->class_dev, &attr_gpio_level);
+
+ class_device_create_file(&gpio_dev->class_dev, &attr_gpio_policy);
+
+ /* set real hardware */
+ if (policy & GPIO_OUTPUT) {
+ switch (init_level) {
+ case 0: gpio_clear_pin(pin_nr); break;
+ case 1: gpio_set_pin(pin_nr); break;
+ default: break;
+ }
+ gpio_dir_output(pin_nr);
+ }
+
+ write_lock(&gpio_list_lock);
+ list_add_tail(&gpio_dev->list, &gpio_list);
+ write_unlock(&gpio_list_lock);
+
+ printk(KERN_INFO "registered gpio%i\n", pin_nr);
+
+ return 0;
+}
+EXPORT_SYMBOL(request_gpio);
+
+/**
+ * free_gpio - unregisters a object of gpio_properties class.
+ *
+ * @pin_nr: pin number to free.
+ *
+ * Unregisters a previously registered via request_gpio object.
+ */
+void free_gpio(unsigned int pin_nr)
+{
+ struct gpio_device *gpio_dev;
+ struct list_head *lact, *ltmp;
+
+ list_for_each_safe(lact, ltmp, &gpio_list) {
+ gpio_dev = list_entry(lact, struct gpio_device, list);
+ if (pin_nr == gpio_dev->props.pin_nr) {
+
+ printk(KERN_INFO "unregistering gpio pin %i\n", pin_nr);
+
+ /* unregister attributes */
+ if (gpio_dev->props.policy & GPIO_USER)
+ class_device_remove_file(&gpio_dev->class_dev,
+ &attr_gpio_level);
+
+ class_device_remove_file(&gpio_dev->class_dev, &attr_gpio_level);
+
+ class_device_unregister(&gpio_dev->class_dev);
+ write_lock(&gpio_list_lock);
+ list_del(&gpio_dev->list);
+ write_unlock(&gpio_list_lock);
+ kfree(gpio_dev);
+ return;
+ }
+ }
+}
+EXPORT_SYMBOL(free_gpio);
+
+void free_all_gpios(void)
+{
+ struct gpio_device *gpio_dev;
+ struct list_head *lact, *ltmp;
+
+ list_for_each_safe(lact, ltmp, &gpio_list) {
+ gpio_dev = list_entry(lact, struct gpio_device, list);
+
+ printk(KERN_INFO "unregistering gpio pin %i\n", gpio_dev->props.pin_nr);
+
+ /* unregister attributes */
+ if (gpio_dev->props.policy & GPIO_USER)
+ class_device_remove_file(&gpio_dev->class_dev,
+ &attr_gpio_level);
+
+ class_device_remove_file(&gpio_dev->class_dev, &attr_gpio_level);
+
+ class_device_unregister(&gpio_dev->class_dev);
+ write_lock(&gpio_list_lock);
+ list_del(&gpio_dev->list);
+ write_unlock(&gpio_list_lock);
+ kfree(gpio_dev);
+ return;
+ }
+}
+EXPORT_SYMBOL(free_all_gpios);
+
+static struct sysdev_class gpio_sysclass = {
+ set_kset_name("gpio"),
+};
+
+static struct sys_device gpio_sys_device = {
+ .id = 0,
+ .cls = &gpio_sysclass,
+};
+
+static int gpio_setup(char *s)
+{
+ char *p, *q = NULL;
+ int pin_nr;
+ unsigned char policy;
+ unsigned char init_level = 0;
+
+ while ((p = strsep(&s, ".,")) != NULL) {
+
+ /* end of command reached? -> next command */
+ if (*p == '\0')
+ continue;
+
+ /* process one command */
+ pin_nr = -1;
+ policy = 0;
+ q = strsep(&p, ":");
+ if (*q == '\0') {
+ printk("%s: invalid token (scanning pin_nr): %s\n", DRIVER_NAME, p);
+ continue;
+ }
+ pin_nr = simple_strtoul(q, NULL, 0); /* FIXME: this doesn't detect if no number is given! */
+ q = strsep(&p, ":");
+ if (*q == '\0') {
+ printk("%s: invalid token (scanning direction): %s\n", DRIVER_NAME, p);
+ continue;
+ }
+ policy |= strncmp(q, "in", strlen(q)) == 0 ? GPIO_INPUT : 0;
+ policy |= strncmp(q, "out", strlen(q)) == 0 ? GPIO_OUTPUT : 0;
+ if (policy == 0) {
+ printk("%s: invalid token (scanning policy): %s\n", DRIVER_NAME, p);
+ continue;
+ }
+ if (policy & GPIO_OUTPUT) {
+ q = strsep(&p, ":");
+ if (*q == '\0') {
+ printk("%s: invalid token (scanning init_level): %s\n", DRIVER_NAME, p);
+ continue;
+ }
+ init_level = 2;
+ if (strncmp(q, "hi", strlen(q)) == 0)
+ init_level = 1;
+ if (strncmp(q, "lo", strlen(q)) == 0)
+ init_level = 0;
+ if (init_level == 2) {
+ printk("%s: invalid token (scanning level_value): %s\n", DRIVER_NAME, p);
+ continue;
+ }
+ }
+ policy |= GPIO_USER;
+ if (request_gpio(pin_nr, "kernel", policy, init_level) != 0) {
+ printk(KERN_ERR
+ "%s: could not register GPIO pins from commandline!\n",
+ DRIVER_NAME);
+ return -EIO;
+ }
+ }
+ return 0;
+}
+
+static int __init gpio_init(void)
+{
+ int ret;
+
+ printk(KERN_INFO "Initialising gpio device class.\n");
+
+ class_register(&gpio_class);
+
+ ret = sysdev_class_register(&gpio_sysclass);
+ if (ret) {
+ printk(KERN_ERR "%s: couldn't register sysdev class, exiting\n", DRIVER_NAME);
+ goto out_sysdev_class;
+ }
+
+ ret = sysdev_register(&gpio_sys_device);
+ if (ret) {
+ printk(KERN_ERR "%s: couldn't register sysdev, exiting\n", DRIVER_NAME);
+ goto out_sysdev_register;
+ }
+
+ if (!create_proc_read_entry ("gpio", 0, 0, gpio_read_proc, NULL)) {
+ printk(KERN_ERR "%s: couldn't register proc entry, exiting\n", DRIVER_NAME);
+ goto out_proc;
+ }
+
+ /* parse command line parameters */
+ printk(KERN_INFO "%s: mapping=", DRIVER_NAME);
+ if (strcmp(mapping,"")) {
+ printk("%s\n", mapping);
+ if (gpio_setup(mapping) != 0) {
+ printk(KERN_ERR "%s: could not register ('mapping=...'), exiting\n", DRIVER_NAME);
+ }
+ } else {
+ printk("EMPTY\n");
+ };
+
+ return ret;
+
+out_proc:
+ sysdev_unregister(&gpio_sys_device);
+out_sysdev_register:
+ sysdev_class_unregister(&gpio_sysclass);
+out_sysdev_class:
+ class_unregister(&gpio_class);
+ return ret;
+}
+
+module_init(gpio_init);
Index: kernel/Makefile
===================================================================
--- a/kernel/Makefile (.../vanilla/linux-2.6.8-rc2) (revision 205)
+++ b/kernel/Makefile (.../linux-pxa/trunks/linux-2.6.8-rc2-trunk) (revision 205)
@@ -23,6 +23,7 @@
obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
obj-$(CONFIG_AUDIT) += audit.o
obj-$(CONFIG_AUDITSYSCALL) += auditsc.o
+obj-$(CONFIG_GPIO) += gpio.o
ifneq ($(CONFIG_IA64),y)
# According to Alan Modra <alan@xxxxxxxxxxxxxxxx>, the -fno-omit-frame-pointer is
Index: include/asm-arm/arch-pxa/gpio.h
===================================================================
--- a/include/asm-arm/arch-pxa/gpio.h (revision 0)
+++ b/include/asm-arm/arch-pxa/gpio.h (revision 205)
@@ -0,0 +1,49 @@
+/*
+ * linux/include/asm-arm/arch-pxa/gpio.h
+ *
+ * Copyright (C) 2004 Robert Schwebel, Pengutronix
+ *
+ * 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 __ARM_PXA_GPIO_H
+#define __ARM_PXA_GPIO_H
+
+#include <linux/kernel.h>
+#include <asm/arch/hardware.h>
+
+#define DEBUG 1
+
+static inline void gpio_set_pin(int gpio_nr)
+{
+ GPSR(gpio_nr) |= GPIO_bit(gpio_nr);
+ return;
+}
+
+static inline void gpio_clear_pin(int gpio_nr)
+{
+ GPCR(gpio_nr) |= GPIO_bit(gpio_nr);
+ return;
+}
+
+static inline void gpio_dir_input(int gpio_nr)
+{
+ GPDR(gpio_nr) &= ~GPIO_bit(gpio_nr);
+ return;
+}
+
+static inline void gpio_dir_output(int gpio_nr)
+{
+ GPDR(gpio_nr) |= GPIO_bit(gpio_nr);
+ return;
+}
+
+static inline int gpio_get_pin(int gpio_nr)
+{
+ return GPLR(gpio_nr) & GPIO_bit(gpio_nr) ? 1:0;
+}
+
+
+#endif
Index: include/linux/gpio.h
===================================================================
--- a/include/linux/gpio.h (revision 0)
+++ b/include/linux/gpio.h (revision 205)
@@ -0,0 +1,27 @@
+/*
+ * include/linux/gpio.h
+ *
+ * Copyright (C) 2004 Robert Schwebel, Pengutronix
+ *
+ * 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 __GPIO_H
+#define __GPIO_H
+
+#include "asm/arch/gpio.h"
+
+/* Values for policy */
+#define GPIO_KERNEL (1<<0)
+#define GPIO_USER (1<<1)
+#define GPIO_INPUT (1<<2)
+#define GPIO_OUTPUT (1<<3)
+
+int request_gpio(unsigned int pin_nr, const char *owner,
+ unsigned char policy, unsigned char init_level);
+
+void free_gpio(unsigned int pin_nr);
+
+#endif
Index: init/Kconfig
===================================================================
--- a/init/Kconfig (.../vanilla/linux-2.6.8-rc2) (revision 205)
+++ b/init/Kconfig (.../linux-pxa/trunks/linux-2.6.8-rc2-trunk) (revision 205)
@@ -294,6 +294,18 @@
If unsure, say N.
+config GPIO
+ bool "GPIO pin support"
+ default y if ARM || PPC
+ default n
+ help
+ Enabling this option adds support for generic GPIO pins. Most
+ System-on-Chip processors have this kind of pins.
+
+ FIXME: write more documentation.
+
+ If unsure, say N.
+
endmenu # General setup