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gpio-bcm-virt.c
213 lines (186 loc) · 5.31 KB
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gpio-bcm-virt.c
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/*
* brcmvirt GPIO driver
*
* Copyright (C) 2012,2013 Dom Cobley <popcornmix@gmail.com>
* Based on gpio-clps711x.c by Alexander Shiyan <shc_work@mail.ru>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <soc/bcm2835/raspberrypi-firmware.h>
#define MODULE_NAME "brcmvirt-gpio"
#define NUM_GPIO 2
struct brcmvirt_gpio {
struct gpio_chip gc;
u32 __iomem *ts_base;
/* two packed 16-bit counts of enabled and disables
Allows host to detect a brief enable that was missed */
u32 enables_disables[NUM_GPIO];
dma_addr_t bus_addr;
};
static int brcmvirt_gpio_dir_in(struct gpio_chip *gc, unsigned off)
{
struct brcmvirt_gpio *gpio;
gpio = container_of(gc, struct brcmvirt_gpio, gc);
return -EINVAL;
}
static int brcmvirt_gpio_dir_out(struct gpio_chip *gc, unsigned off, int val)
{
struct brcmvirt_gpio *gpio;
gpio = container_of(gc, struct brcmvirt_gpio, gc);
return 0;
}
static int brcmvirt_gpio_get(struct gpio_chip *gc, unsigned off)
{
struct brcmvirt_gpio *gpio;
unsigned v;
gpio = container_of(gc, struct brcmvirt_gpio, gc);
v = readl(gpio->ts_base + off);
return (v >> off) & 1;
}
static void brcmvirt_gpio_set(struct gpio_chip *gc, unsigned off, int val)
{
struct brcmvirt_gpio *gpio;
u16 enables, disables;
s16 diff;
bool lit;
gpio = container_of(gc, struct brcmvirt_gpio, gc);
enables = gpio->enables_disables[off] >> 16;
disables = gpio->enables_disables[off] >> 0;
diff = (s16)(enables - disables);
lit = diff > 0;
if ((val && lit) || (!val && !lit))
return;
if (val)
enables++;
else
disables++;
diff = (s16)(enables - disables);
BUG_ON(diff != 0 && diff != 1);
gpio->enables_disables[off] = (enables << 16) | (disables << 0);
writel(gpio->enables_disables[off], gpio->ts_base + off);
}
static int brcmvirt_gpio_probe(struct platform_device *pdev)
{
int err = 0;
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
struct device_node *fw_node;
struct rpi_firmware *fw;
struct brcmvirt_gpio *ucb;
u32 gpiovirtbuf;
fw_node = of_parse_phandle(np, "firmware", 0);
if (!fw_node) {
dev_err(dev, "Missing firmware node\n");
return -ENOENT;
}
fw = rpi_firmware_get(fw_node);
if (!fw)
return -EPROBE_DEFER;
ucb = devm_kzalloc(dev, sizeof *ucb, GFP_KERNEL);
if (!ucb) {
err = -EINVAL;
goto out;
}
ucb->ts_base = dma_zalloc_coherent(NULL, PAGE_SIZE, &ucb->bus_addr, GFP_KERNEL);
if (!ucb->ts_base) {
pr_err("[%s]: failed to dma_alloc_coherent(%ld)\n",
__func__, PAGE_SIZE);
err = -ENOMEM;
goto out;
}
gpiovirtbuf = (u32)ucb->bus_addr;
err = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_SET_GPIOVIRTBUF,
&gpiovirtbuf, sizeof(gpiovirtbuf));
if (err || gpiovirtbuf != 0) {
dev_warn(dev, "Failed to set gpiovirtbuf, trying to get err:%x\n", err);
dma_free_coherent(NULL, PAGE_SIZE, ucb->ts_base, ucb->bus_addr);
ucb->ts_base = 0;
ucb->bus_addr = 0;
}
if (!ucb->ts_base) {
err = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_GET_GPIOVIRTBUF,
&gpiovirtbuf, sizeof(gpiovirtbuf));
if (err) {
dev_err(dev, "Failed to get gpiovirtbuf\n");
goto out;
}
if (!gpiovirtbuf) {
dev_err(dev, "No virtgpio buffer\n");
err = -ENOENT;
goto out;
}
// mmap the physical memory
gpiovirtbuf &= ~0xc0000000;
ucb->ts_base = ioremap(gpiovirtbuf, 4096);
if (ucb->ts_base == NULL) {
dev_err(dev, "Failed to map physical address\n");
err = -ENOENT;
goto out;
}
ucb->bus_addr = 0;
}
ucb->gc.label = MODULE_NAME;
ucb->gc.owner = THIS_MODULE;
//ucb->gc.dev = dev;
ucb->gc.of_node = np;
ucb->gc.base = 100;
ucb->gc.ngpio = NUM_GPIO;
ucb->gc.direction_input = brcmvirt_gpio_dir_in;
ucb->gc.direction_output = brcmvirt_gpio_dir_out;
ucb->gc.get = brcmvirt_gpio_get;
ucb->gc.set = brcmvirt_gpio_set;
ucb->gc.can_sleep = true;
err = gpiochip_add(&ucb->gc);
if (err)
goto out;
platform_set_drvdata(pdev, ucb);
return 0;
out:
if (ucb->bus_addr) {
dma_free_coherent(NULL, PAGE_SIZE, ucb->ts_base, ucb->bus_addr);
ucb->bus_addr = 0;
ucb->ts_base = NULL;
} else if (ucb->ts_base) {
iounmap(ucb->ts_base);
ucb->ts_base = NULL;
}
return err;
}
static int brcmvirt_gpio_remove(struct platform_device *pdev)
{
int err = 0;
struct brcmvirt_gpio *ucb = platform_get_drvdata(pdev);
gpiochip_remove(&ucb->gc);
if (ucb->bus_addr)
dma_free_coherent(NULL, PAGE_SIZE, ucb->ts_base, ucb->bus_addr);
else if (ucb->ts_base)
iounmap(ucb->ts_base);
return err;
}
static const struct of_device_id __maybe_unused brcmvirt_gpio_ids[] = {
{ .compatible = "brcm,bcm2835-virtgpio" },
{ }
};
MODULE_DEVICE_TABLE(of, brcmvirt_gpio_ids);
static struct platform_driver brcmvirt_gpio_driver = {
.driver = {
.name = MODULE_NAME,
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(brcmvirt_gpio_ids),
},
.probe = brcmvirt_gpio_probe,
.remove = brcmvirt_gpio_remove,
};
module_platform_driver(brcmvirt_gpio_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dom Cobley <popcornmix@gmail.com>");
MODULE_DESCRIPTION("brcmvirt GPIO driver");
MODULE_ALIAS("platform:brcmvirt-gpio");