linux/drivers/gpio/gpio-spear-spics.c
Linus Torvalds e6b5be2be4 Driver core patches for 3.19-rc1
Here's the set of driver core patches for 3.19-rc1.
 
 They are dominated by the removal of the .owner field in platform
 drivers.  They touch a lot of files, but they are "simple" changes, just
 removing a line in a structure.
 
 Other than that, a few minor driver core and debugfs changes.  There are
 some ath9k patches coming in through this tree that have been acked by
 the wireless maintainers as they relied on the debugfs changes.
 
 Everything has been in linux-next for a while.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core update from Greg KH:
 "Here's the set of driver core patches for 3.19-rc1.

  They are dominated by the removal of the .owner field in platform
  drivers.  They touch a lot of files, but they are "simple" changes,
  just removing a line in a structure.

  Other than that, a few minor driver core and debugfs changes.  There
  are some ath9k patches coming in through this tree that have been
  acked by the wireless maintainers as they relied on the debugfs
  changes.

  Everything has been in linux-next for a while"

* tag 'driver-core-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (324 commits)
  Revert "ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries"
  fs: debugfs: add forward declaration for struct device type
  firmware class: Deletion of an unnecessary check before the function call "vunmap"
  firmware loader: fix hung task warning dump
  devcoredump: provide a one-way disable function
  device: Add dev_<level>_once variants
  ath: ath9k: use debugfs_create_devm_seqfile() helper for seq_file entries
  ath: use seq_file api for ath9k debugfs files
  debugfs: add helper function to create device related seq_file
  drivers/base: cacheinfo: remove noisy error boot message
  Revert "core: platform: add warning if driver has no owner"
  drivers: base: support cpu cache information interface to userspace via sysfs
  drivers: base: add cpu_device_create to support per-cpu devices
  topology: replace custom attribute macros with standard DEVICE_ATTR*
  cpumask: factor out show_cpumap into separate helper function
  driver core: Fix unbalanced device reference in drivers_probe
  driver core: fix race with userland in device_add()
  sysfs/kernfs: make read requests on pre-alloc files use the buffer.
  sysfs/kernfs: allow attributes to request write buffer be pre-allocated.
  fs: sysfs: return EGBIG on write if offset is larger than file size
  ...
2014-12-14 16:10:09 -08:00

208 lines
5.5 KiB
C

/*
* SPEAr platform SPI chipselect abstraction over gpiolib
*
* Copyright (C) 2012 ST Microelectronics
* Shiraz Hashim <shiraz.linux.kernel@gmail.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/types.h>
/* maximum chipselects */
#define NUM_OF_GPIO 4
/*
* Provision is available on some SPEAr SoCs to control ARM PL022 spi cs
* through system registers. This register lies outside spi (pl022)
* address space into system registers.
*
* It provides control for spi chip select lines so that any chipselect
* (out of 4 possible chipselects in pl022) can be made low to select
* the particular slave.
*/
/**
* struct spear_spics - represents spi chip select control
* @base: base address
* @perip_cfg: configuration register
* @sw_enable_bit: bit to enable s/w control over chipselects
* @cs_value_bit: bit to program high or low chipselect
* @cs_enable_mask: mask to select bits required to select chipselect
* @cs_enable_shift: bit pos of cs_enable_mask
* @use_count: use count of a spi controller cs lines
* @last_off: stores last offset caller of set_value()
* @chip: gpio_chip abstraction
*/
struct spear_spics {
void __iomem *base;
u32 perip_cfg;
u32 sw_enable_bit;
u32 cs_value_bit;
u32 cs_enable_mask;
u32 cs_enable_shift;
unsigned long use_count;
int last_off;
struct gpio_chip chip;
};
/* gpio framework specific routines */
static int spics_get_value(struct gpio_chip *chip, unsigned offset)
{
return -ENXIO;
}
static void spics_set_value(struct gpio_chip *chip, unsigned offset, int value)
{
struct spear_spics *spics = container_of(chip, struct spear_spics,
chip);
u32 tmp;
/* select chip select from register */
tmp = readl_relaxed(spics->base + spics->perip_cfg);
if (spics->last_off != offset) {
spics->last_off = offset;
tmp &= ~(spics->cs_enable_mask << spics->cs_enable_shift);
tmp |= offset << spics->cs_enable_shift;
}
/* toggle chip select line */
tmp &= ~(0x1 << spics->cs_value_bit);
tmp |= value << spics->cs_value_bit;
writel_relaxed(tmp, spics->base + spics->perip_cfg);
}
static int spics_direction_input(struct gpio_chip *chip, unsigned offset)
{
return -ENXIO;
}
static int spics_direction_output(struct gpio_chip *chip, unsigned offset,
int value)
{
spics_set_value(chip, offset, value);
return 0;
}
static int spics_request(struct gpio_chip *chip, unsigned offset)
{
struct spear_spics *spics = container_of(chip, struct spear_spics,
chip);
u32 tmp;
if (!spics->use_count++) {
tmp = readl_relaxed(spics->base + spics->perip_cfg);
tmp |= 0x1 << spics->sw_enable_bit;
tmp |= 0x1 << spics->cs_value_bit;
writel_relaxed(tmp, spics->base + spics->perip_cfg);
}
return 0;
}
static void spics_free(struct gpio_chip *chip, unsigned offset)
{
struct spear_spics *spics = container_of(chip, struct spear_spics,
chip);
u32 tmp;
if (!--spics->use_count) {
tmp = readl_relaxed(spics->base + spics->perip_cfg);
tmp &= ~(0x1 << spics->sw_enable_bit);
writel_relaxed(tmp, spics->base + spics->perip_cfg);
}
}
static int spics_gpio_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct spear_spics *spics;
struct resource *res;
int ret;
spics = devm_kzalloc(&pdev->dev, sizeof(*spics), GFP_KERNEL);
if (!spics)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
spics->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(spics->base))
return PTR_ERR(spics->base);
if (of_property_read_u32(np, "st-spics,peripcfg-reg",
&spics->perip_cfg))
goto err_dt_data;
if (of_property_read_u32(np, "st-spics,sw-enable-bit",
&spics->sw_enable_bit))
goto err_dt_data;
if (of_property_read_u32(np, "st-spics,cs-value-bit",
&spics->cs_value_bit))
goto err_dt_data;
if (of_property_read_u32(np, "st-spics,cs-enable-mask",
&spics->cs_enable_mask))
goto err_dt_data;
if (of_property_read_u32(np, "st-spics,cs-enable-shift",
&spics->cs_enable_shift))
goto err_dt_data;
platform_set_drvdata(pdev, spics);
spics->chip.ngpio = NUM_OF_GPIO;
spics->chip.base = -1;
spics->chip.request = spics_request;
spics->chip.free = spics_free;
spics->chip.direction_input = spics_direction_input;
spics->chip.direction_output = spics_direction_output;
spics->chip.get = spics_get_value;
spics->chip.set = spics_set_value;
spics->chip.label = dev_name(&pdev->dev);
spics->chip.dev = &pdev->dev;
spics->chip.owner = THIS_MODULE;
spics->last_off = -1;
ret = gpiochip_add(&spics->chip);
if (ret) {
dev_err(&pdev->dev, "unable to add gpio chip\n");
return ret;
}
dev_info(&pdev->dev, "spear spics registered\n");
return 0;
err_dt_data:
dev_err(&pdev->dev, "DT probe failed\n");
return -EINVAL;
}
static const struct of_device_id spics_gpio_of_match[] = {
{ .compatible = "st,spear-spics-gpio" },
{}
};
MODULE_DEVICE_TABLE(of, spics_gpio_of_match);
static struct platform_driver spics_gpio_driver = {
.probe = spics_gpio_probe,
.driver = {
.name = "spear-spics-gpio",
.of_match_table = spics_gpio_of_match,
},
};
static int __init spics_gpio_init(void)
{
return platform_driver_register(&spics_gpio_driver);
}
subsys_initcall(spics_gpio_init);
MODULE_AUTHOR("Shiraz Hashim <shiraz.linux.kernel@gmail.com>");
MODULE_DESCRIPTION("STMicroelectronics SPEAr SPI Chip Select Abstraction");
MODULE_LICENSE("GPL");