Provides a simple GPIO char driver for the AMD CS5535, modeled after
the scx200_gpio driver.
Signed-off-by: Ben Gardner <[email protected]>
drivers/char/Kconfig | 9 +
drivers/char/Makefile | 1
drivers/char/cs5535_gpio.c | 209 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 219 insertions(+)
Index: linux-2.6.14/drivers/char/cs5535_gpio.c
===================================================================
--- /dev/null
+++ linux-2.6.14/drivers/char/cs5535_gpio.c
@@ -0,0 +1,209 @@
+/*
+ * linux/drivers/char/cs5535_gpio.c
+ *
+ * AMD CS5535 GPIO driver.
+ * Allows a user space process to play with the GPIO pins.
+ *
+ * Heavily inspired by scx200_gpio, by Christer Weinigel
+ *
+ * Copyright (c) 2005 Ben Gardner <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the smems of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ */
+
+#include <linux/config.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/cdev.h>
+#include <linux/ioport.h>
+#include <asm/uaccess.h>
+#include <asm/io.h>
+
+
+#define NAME "cs5535_gpio"
+
+MODULE_AUTHOR("Ben Gardner <[email protected]>");
+MODULE_DESCRIPTION("AMD CS5535 GPIO Pin Driver");
+MODULE_LICENSE("GPL");
+
+static int major = 0; /* default to dynamic major */
+module_param(major, int, 0);
+MODULE_PARM_DESC(major, "Major device number");
+
+/* These are defined in cs5535.c */
+extern u32 cs5535_gpio_base;
+extern u32 cs5535_gpio_mask;
+
+static struct cdev cs5535_gpio_cdev;
+
+/* reserve 32 entries even though some aren't usable */
+#define CS5535_GPIO_COUNT 32
+
+/* IO block size */
+#define CS5535_GPIO_SIZE 256
+
+struct gpio_regmap {
+ u32 rd_offset;
+ u32 wr_offset;
+ char on;
+ char off;
+};
+static struct gpio_regmap rm[] =
+{
+ { 0x30, 0x00, '1', '0' }, /* GPIOx_READ_BACK / GPIOx_OUT_VAL */
+ { 0x20, 0x20, 'I', 'i' }, /* GPIOx_IN_EN */
+ { 0x04, 0x04, 'O', 'o' }, /* GPIOx_OUT_EN */
+ { 0x08, 0x08, 't', 'T' }, /* GPIOx_OUT_OD_EN */
+ { 0x18, 0x18, 'P', 'p' }, /* GPIOL_OUT_PU_EN */
+ { 0x1c, 0x1c, 'D', 'd' }, /* GPIOx_OUT_PD_EN */
+};
+
+
+/**
+ * Gets the register offset for the GPIO bank.
+ * Low (0-15) starts at 0x00, high (16-31) starts at 0x80
+ */
+static inline u32 cs5535_lowhigh_base(int reg)
+{
+ return (reg & 0x10) << 3;
+}
+
+static ssize_t cs5535_gpio_write(struct file *file, const char __user *data,
+ size_t len, loff_t *ppos)
+{
+ u32 m = iminor(file->f_dentry->d_inode);
+ int i, j;
+ u32 base = cs5535_gpio_base + cs5535_lowhigh_base(m);
+ u32 m0, m1;
+ char c;
+
+ /**
+ * Creates the mask for atomic bit programming.
+ * The high 16 bits and the low 16 bits are used to set the mask.
+ * For example, GPIO 15 maps to 31,15: 0,1 => On; 1,0=> Off
+ */
+ m1 = 1 << (m & 0x0F);
+ m0 = m1 << 16;
+
+ for (i = 0; i < len; ++i) {
+ if (get_user(c, data+i))
+ return -EFAULT;
+
+ for (j = 0; j < ARRAY_SIZE(rm); j++) {
+ if (c == rm[j].on) {
+ outl(m1, base + rm[j].wr_offset);
+ break;
+ } else if (c == rm[j].off) {
+ outl(m0, base + rm[j].wr_offset);
+ break;
+ }
+ }
+ }
+ *ppos = 0;
+ return len;
+}
+
+static ssize_t cs5535_gpio_read(struct file *file, char __user *buf,
+ size_t len, loff_t *ppos)
+{
+ u32 m = iminor(file->f_dentry->d_inode);
+ u32 base = cs5535_gpio_base + cs5535_lowhigh_base(m);
+ int mask = 1 << (m & 0x0f);
+ int i;
+ char ch;
+ ssize_t count = 0;
+
+ if (*ppos >= ARRAY_SIZE(rm))
+ return 0;
+
+ for (i = *ppos; (i < (*ppos + len)) && (i < ARRAY_SIZE(rm)); i++) {
+ ch = (inl(base + rm[i].rd_offset) & mask) ?
+ rm[i].on : rm[i].off;
+
+ if (put_user(ch, buf+count))
+ return -EFAULT;
+
+ count++;
+ }
+
+ /* add a line-feed if there is room */
+ if ((i == ARRAY_SIZE(rm)) && (count < len)) {
+ put_user('\n', buf + count);
+ count++;
+ }
+
+ *ppos += count;
+ return count;
+}
+
+static int cs5535_gpio_open(struct inode *inode, struct file *file)
+{
+ u32 m = iminor(inode);
+
+ /* the mask says which pins are usable by this driver */
+ if ((cs5535_gpio_mask & (1 << m)) == 0)
+ return -EINVAL;
+
+ return nonseekable_open(inode, file);
+}
+
+static struct file_operations cs5535_gpio_fops = {
+ .owner = THIS_MODULE,
+ .write = cs5535_gpio_write,
+ .read = cs5535_gpio_read,
+ .open = cs5535_gpio_open
+};
+
+static int __init cs5535_gpio_init(void)
+{
+ dev_t dev_id;
+ int retval;
+
+ if (cs5535_gpio_base == 0) {
+ printk(KERN_WARNING NAME ": GPIO not available\n");
+ return -ENODEV;
+ }
+
+ if (request_region(cs5535_gpio_base, CS5535_GPIO_SIZE, NAME) == 0) {
+ printk(KERN_ERR NAME ": can't allocate I/O for GPIO\n");
+ return -ENODEV;
+ }
+
+ printk(KERN_DEBUG NAME ": AMD CS5535 GPIO Driver: mask=%x\n",
+ cs5535_gpio_mask);
+
+ if (major) {
+ dev_id = MKDEV(major, 0);
+ retval = register_chrdev_region(dev_id, CS5535_GPIO_COUNT,
+ NAME);
+ } else {
+ retval = alloc_chrdev_region(&dev_id, 0, CS5535_GPIO_COUNT,
+ NAME);
+ major = MAJOR(dev_id);
+ }
+
+ if (retval) {
+ release_region(cs5535_gpio_base, CS5535_GPIO_SIZE);
+ return -1;
+ }
+
+ cdev_init(&cs5535_gpio_cdev, &cs5535_gpio_fops);
+ cdev_add(&cs5535_gpio_cdev, dev_id, CS5535_GPIO_COUNT);
+
+ return 0;
+}
+
+static void __exit cs5535_gpio_cleanup(void)
+{
+ dev_t dev_id = MKDEV(major, 0);
+ unregister_chrdev_region(dev_id, CS5535_GPIO_COUNT);
+ release_region(cs5535_gpio_base, CS5535_GPIO_SIZE);
+}
+
+module_init(cs5535_gpio_init);
+module_exit(cs5535_gpio_cleanup);
Index: linux-2.6.14/drivers/char/Kconfig
===================================================================
--- linux-2.6.14.orig/drivers/char/Kconfig
+++ linux-2.6.14/drivers/char/Kconfig
@@ -936,6 +936,15 @@ config SCx200_GPIO
If compiled as a module, it will be called scx200_gpio.
+config CS5535_GPIO
+ tristate "AMD CS5535 GPIO (Geode GX)"
+ depends on CS5535
+ help
+ Give userspace access to the GPIO pins on the AMD CS5535 Geode GX
+ companion device.
+
+ If compiled as a module, it will be called cs5535_gpio.
+
config GPIO_VR41XX
tristate "NEC VR4100 series General-purpose I/O Unit support"
depends on CPU_VR41XX
Index: linux-2.6.14/drivers/char/Makefile
===================================================================
--- linux-2.6.14.orig/drivers/char/Makefile
+++ linux-2.6.14/drivers/char/Makefile
@@ -81,6 +81,7 @@ obj-$(CONFIG_PPDEV) += ppdev.o
obj-$(CONFIG_NWBUTTON) += nwbutton.o
obj-$(CONFIG_NWFLASH) += nwflash.o
obj-$(CONFIG_SCx200_GPIO) += scx200_gpio.o
+obj-$(CONFIG_CS5535_GPIO) += cs5535_gpio.o
obj-$(CONFIG_GPIO_VR41XX) += vr41xx_giu.o
obj-$(CONFIG_TANBAC_TB0219) += tb0219.o
obj-$(CONFIG_TELCLOCK) += tlclk.o
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