[PATCH] i386: GPIO driver for AMD CS5535/CS5536

A simple driver for the CS5535 and CS5536 that allows a user-space program
to manipulate GPIO pins.  The CS5535/CS5536 chips are Geode processor
companion devices.

Signed-off-by: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Richard Knutsson <ricknu-0@student.ltu.se>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 250 insertions, 0 deletions

diff --git a/drivers/char/cs5535_gpio.c b/drivers/char/cs5535_gpio.c
new file mode 100644
index 000000000000..5d72f50de1ac
--- /dev/null
+++ b/drivers/char/cs5535_gpio.c
@@ -0,0 +1,250 @@
+/*
+ * AMD CS5535/CS5536 GPIO driver.
+ * Allows a user space process to play with the GPIO pins.
+ *
+ * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com>
+ *
+ * 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/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 <linux/pci.h>
+#include <asm/uaccess.h>
+#include <asm/io.h>
+
+
+#define NAME                    "cs5535_gpio"
+
+MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
+MODULE_DESCRIPTION("AMD CS5535/CS5536 GPIO Pin Driver");
+MODULE_LICENSE("GPL");
+
+static int major;
+module_param(major, int, 0);
+MODULE_PARM_DESC(major, "Major device number");
+
+static ulong mask;
+module_param(mask, ulong, 0);
+MODULE_PARM_DESC(mask, "GPIO channel mask");
+
+#define MSR_LBAR_GPIO           0x5140000C
+
+static u32 gpio_base;
+
+static struct pci_device_id divil_pci[] = {
+        { PCI_DEVICE(PCI_VENDOR_ID_NS,  PCI_DEVICE_ID_NS_CS5535_ISA) },
+        { PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA) },
+        { } /* NULL entry */
+};
+
+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' },       /* GPIOx_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 = 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 = gpio_base + cs5535_lowhigh_base(m);
+        int     rd_bit = 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) & rd_bit) ?
+                     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 ((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;
+        u32     low, hi;
+        int     retval;
+
+        if (pci_dev_present(divil_pci) == 0) {
+                printk(KERN_WARNING NAME ": DIVIL not found\n");
+                return -ENODEV;
+        }
+
+        /* Grab the GPIO I/O range */
+        rdmsr(MSR_LBAR_GPIO, low, hi);
+
+        /* Check the mask and whether GPIO is enabled (sanity check) */
+        if (hi != 0x0000f001) {
+                printk(KERN_WARNING NAME ": GPIO not enabled\n");
+                return -ENODEV;
+        }
+
+        /* Mask off the IO base address */
+        gpio_base = low & 0x0000ff00;
+
+        /**
+         * Some GPIO pins
+         *  31-29,23 : reserved (always mask out)
+         *  28       : Power Button
+         *  26       : PME#
+         *  22-16    : LPC
+         *  14,15    : SMBus
+         *  9,8      : UART1
+         *  7        : PCI INTB
+         *  3,4      : UART2/DDC
+         *  2        : IDE_IRQ0
+         *  0        : PCI INTA
+         *
+         * If a mask was not specified, be conservative and only allow:
+         *  1,2,5,6,10-13,24,25,27
+         */
+        if (mask != 0)
+                mask &= 0x1f7fffff;
+        else
+                mask = 0x0b003c66;
+
+        if (request_region(gpio_base, CS5535_GPIO_SIZE, NAME) == 0) {
+                printk(KERN_ERR NAME ": can't allocate I/O for GPIO\n");
+                return -ENODEV;
+        }
+
+        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(gpio_base, CS5535_GPIO_SIZE);
+                return -1;
+        }
+
+        printk(KERN_DEBUG NAME ": base=%#x mask=%#lx major=%d\n",
+               gpio_base, mask, major);
+
+        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);
+        if (gpio_base != 0)
+                release_region(gpio_base, CS5535_GPIO_SIZE);
+}
+
+module_init(cs5535_gpio_init);
+module_exit(cs5535_gpio_cleanup);