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linux/drivers/gpio/cs5535-gpio.c
Andres Salomon 853ff88324 cs5535-gpio: apply CS5536 errata workaround for GPIOs 
The AMD Geode CS5536 Companion Device Silicon Revision B1 Specification
Update mentions the follow as issue #36:

 "Atomic write transactions to the atomic GPIO High Bank Feature Bit
  registers should only affect the bits selected [...]"

 "after Suspend, an atomic write transaction [...] will clear all
  non-selected bits of the accessed register."

In other words, writing to the high bank for a single GPIO bit will
clear every other GPIO bit (but only sometimes after a suspend).

The workaround described is obvious and simple; do a read-modify-write.
This patch does that, and documents why we're doing it.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-12-02 14:51:15 -08:00

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/*
* AMD CS5535/CS5536 GPIO driver
* Copyright (C) 2006 Advanced Micro Devices, Inc.
* Copyright (C) 2007-2009 Andres Salomon <dilinger@collabora.co.uk>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public License
* as published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/gpio.h>
#include <linux/io.h>
#include <linux/cs5535.h>
#define DRV_NAME "cs5535-gpio"
#define GPIO_BAR 1
/*
* 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
* 1 : AC_BEEP
* 0 : PCI INTA
*
* If a mask was not specified, allow all except
* reserved and Power Button
*/
#define GPIO_DEFAULT_MASK 0x0F7FFFFF
static ulong mask = GPIO_DEFAULT_MASK;
module_param_named(mask, mask, ulong, 0444);
MODULE_PARM_DESC(mask, "GPIO channel mask.");
static struct cs5535_gpio_chip {
struct gpio_chip chip;
resource_size_t base;
struct pci_dev *pdev;
spinlock_t lock;
} cs5535_gpio_chip;
/*
* The CS5535/CS5536 GPIOs support a number of extra features not defined
* by the gpio_chip API, so these are exported. For a full list of the
* registers, see include/linux/cs5535.h.
*/
static void errata_outl(u32 val, unsigned long addr)
{
/*
* According to the CS5536 errata (#36), after suspend
* a write to the high bank GPIO register will clear all
* non-selected bits; the recommended workaround is a
* read-modify-write operation.
*/
val |= inl(addr);
outl(val, addr);
}
static void __cs5535_gpio_set(struct cs5535_gpio_chip *chip, unsigned offset,
unsigned int reg)
{
if (offset < 16)
/* low bank register */
outl(1 << offset, chip->base + reg);
else
/* high bank register */
errata_outl(1 << (offset - 16), chip->base + 0x80 + reg);
}
void cs5535_gpio_set(unsigned offset, unsigned int reg)
{
struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
unsigned long flags;
spin_lock_irqsave(&chip->lock, flags);
__cs5535_gpio_set(chip, offset, reg);
spin_unlock_irqrestore(&chip->lock, flags);
}
EXPORT_SYMBOL_GPL(cs5535_gpio_set);
static void __cs5535_gpio_clear(struct cs5535_gpio_chip *chip, unsigned offset,
unsigned int reg)
{
if (offset < 16)
/* low bank register */
outl(1 << (offset + 16), chip->base + reg);
else
/* high bank register */
errata_outl(1 << offset, chip->base + 0x80 + reg);
}
void cs5535_gpio_clear(unsigned offset, unsigned int reg)
{
struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
unsigned long flags;
spin_lock_irqsave(&chip->lock, flags);
__cs5535_gpio_clear(chip, offset, reg);
spin_unlock_irqrestore(&chip->lock, flags);
}
EXPORT_SYMBOL_GPL(cs5535_gpio_clear);
int cs5535_gpio_isset(unsigned offset, unsigned int reg)
{
struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
unsigned long flags;
long val;
spin_lock_irqsave(&chip->lock, flags);
if (offset < 16)
/* low bank register */
val = inl(chip->base + reg);
else {
/* high bank register */
val = inl(chip->base + 0x80 + reg);
offset -= 16;
}
spin_unlock_irqrestore(&chip->lock, flags);
return (val & (1 << offset)) ? 1 : 0;
}
EXPORT_SYMBOL_GPL(cs5535_gpio_isset);
/*
* Generic gpio_chip API support.
*/
static int chip_gpio_request(struct gpio_chip *c, unsigned offset)
{
struct cs5535_gpio_chip *chip = (struct cs5535_gpio_chip *) c;
unsigned long flags;
spin_lock_irqsave(&chip->lock, flags);
/* check if this pin is available */
if ((mask & (1 << offset)) == 0) {
dev_info(&chip->pdev->dev,
"pin %u is not available (check mask)\n", offset);
spin_unlock_irqrestore(&chip->lock, flags);
return -EINVAL;
}
/* disable output aux 1 & 2 on this pin */
__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX1);
__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX2);
/* disable input aux 1 on this pin */
__cs5535_gpio_clear(chip, offset, GPIO_INPUT_AUX1);
spin_unlock_irqrestore(&chip->lock, flags);
return 0;
}
static int chip_gpio_get(struct gpio_chip *chip, unsigned offset)
{
return cs5535_gpio_isset(offset, GPIO_READ_BACK);
}
static void chip_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
{
if (val)
cs5535_gpio_set(offset, GPIO_OUTPUT_VAL);
else
cs5535_gpio_clear(offset, GPIO_OUTPUT_VAL);
}
static int chip_direction_input(struct gpio_chip *c, unsigned offset)
{
struct cs5535_gpio_chip *chip = (struct cs5535_gpio_chip *) c;
unsigned long flags;
spin_lock_irqsave(&chip->lock, flags);
__cs5535_gpio_set(chip, offset, GPIO_INPUT_ENABLE);
__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_ENABLE);
spin_unlock_irqrestore(&chip->lock, flags);
return 0;
}
static int chip_direction_output(struct gpio_chip *c, unsigned offset, int val)
{
struct cs5535_gpio_chip *chip = (struct cs5535_gpio_chip *) c;
unsigned long flags;
spin_lock_irqsave(&chip->lock, flags);
__cs5535_gpio_set(chip, offset, GPIO_INPUT_ENABLE);
__cs5535_gpio_set(chip, offset, GPIO_OUTPUT_ENABLE);
if (val)
__cs5535_gpio_set(chip, offset, GPIO_OUTPUT_VAL);
else
__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_VAL);
spin_unlock_irqrestore(&chip->lock, flags);
return 0;
}
static const char * const cs5535_gpio_names[] = {
"GPIO0", "GPIO1", "GPIO2", "GPIO3",
"GPIO4", "GPIO5", "GPIO6", "GPIO7",
"GPIO8", "GPIO9", "GPIO10", "GPIO11",
"GPIO12", "GPIO13", "GPIO14", "GPIO15",
"GPIO16", "GPIO17", "GPIO18", "GPIO19",
"GPIO20", "GPIO21", "GPIO22", NULL,
"GPIO24", "GPIO25", "GPIO26", "GPIO27",
"GPIO28", NULL, NULL, NULL,
};
static struct cs5535_gpio_chip cs5535_gpio_chip = {
.chip = {
.owner = THIS_MODULE,
.label = DRV_NAME,
.base = 0,
.ngpio = 32,
.names = cs5535_gpio_names,
.request = chip_gpio_request,
.get = chip_gpio_get,
.set = chip_gpio_set,
.direction_input = chip_direction_input,
.direction_output = chip_direction_output,
},
};
static int __init cs5535_gpio_probe(struct pci_dev *pdev,
const struct pci_device_id *pci_id)
{
int err;
ulong mask_orig = mask;
/* There are two ways to get the GPIO base address; one is by
* fetching it from MSR_LBAR_GPIO, the other is by reading the
* PCI BAR info. The latter method is easier (especially across
* different architectures), so we'll stick with that for now. If
* it turns out to be unreliable in the face of crappy BIOSes, we
* can always go back to using MSRs.. */
err = pci_enable_device_io(pdev);
if (err) {
dev_err(&pdev->dev, "can't enable device IO\n");
goto done;
}
err = pci_request_region(pdev, GPIO_BAR, DRV_NAME);
if (err) {
dev_err(&pdev->dev, "can't alloc PCI BAR #%d\n", GPIO_BAR);
goto done;
}
/* set up the driver-specific struct */
cs5535_gpio_chip.base = pci_resource_start(pdev, GPIO_BAR);
cs5535_gpio_chip.pdev = pdev;
spin_lock_init(&cs5535_gpio_chip.lock);
dev_info(&pdev->dev, "allocated PCI BAR #%d: base 0x%llx\n", GPIO_BAR,
(unsigned long long) cs5535_gpio_chip.base);
/* mask out reserved pins */
mask &= 0x1F7FFFFF;
/* do not allow pin 28, Power Button, as there's special handling
* in the PMC needed. (note 12, p. 48) */
mask &= ~(1 << 28);
if (mask_orig != mask)
dev_info(&pdev->dev, "mask changed from 0x%08lX to 0x%08lX\n",
mask_orig, mask);
/* finally, register with the generic GPIO API */
err = gpiochip_add(&cs5535_gpio_chip.chip);
if (err)
goto release_region;
dev_info(&pdev->dev, DRV_NAME ": GPIO support successfully loaded.\n");
return 0;
release_region:
pci_release_region(pdev, GPIO_BAR);
done:
return err;
}
static void __exit cs5535_gpio_remove(struct pci_dev *pdev)
{
int err;
err = gpiochip_remove(&cs5535_gpio_chip.chip);
if (err) {
/* uhh? */
dev_err(&pdev->dev, "unable to remove gpio_chip?\n");
}
pci_release_region(pdev, GPIO_BAR);
}
static struct pci_device_id cs5535_gpio_pci_tbl[] = {
{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_CS5535_ISA) },
{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA) },
{ 0, },
};
MODULE_DEVICE_TABLE(pci, cs5535_gpio_pci_tbl);
/*
* We can't use the standard PCI driver registration stuff here, since
* that allows only one driver to bind to each PCI device (and we want
* multiple drivers to be able to bind to the device). Instead, manually
* scan for the PCI device, request a single region, and keep track of the
* devices that we're using.
*/
static int __init cs5535_gpio_scan_pci(void)
{
struct pci_dev *pdev;
int err = -ENODEV;
int i;
for (i = 0; i < ARRAY_SIZE(cs5535_gpio_pci_tbl); i++) {
pdev = pci_get_device(cs5535_gpio_pci_tbl[i].vendor,
cs5535_gpio_pci_tbl[i].device, NULL);
if (pdev) {
err = cs5535_gpio_probe(pdev, &cs5535_gpio_pci_tbl[i]);
if (err)
pci_dev_put(pdev);
/* we only support a single CS5535/6 southbridge */
break;
}
}
return err;
}
static void __exit cs5535_gpio_free_pci(void)
{
cs5535_gpio_remove(cs5535_gpio_chip.pdev);
pci_dev_put(cs5535_gpio_chip.pdev);
}
static int __init cs5535_gpio_init(void)
{
return cs5535_gpio_scan_pci();
}
static void __exit cs5535_gpio_exit(void)
{
cs5535_gpio_free_pci();
}
module_init(cs5535_gpio_init);
module_exit(cs5535_gpio_exit);
MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
MODULE_DESCRIPTION("AMD CS5535/CS5536 GPIO driver");
MODULE_LICENSE("GPL");
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