74x164_gpio.c
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// SPDX-License-Identifier: GPL-2.0+
/*
* Take drivers/gpio/gpio-74x164.c as reference.
*
* 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
*
* Copyright (C) 2016 Peng Fan <van.freenix@gmail.com>
*
*/
#include <common.h>
#include <errno.h>
#include <dm.h>
#include <fdtdec.h>
#include <malloc.h>
#include <asm/gpio.h>
#include <asm/io.h>
#include <dm/device_compat.h>
#include <dt-bindings/gpio/gpio.h>
#include <spi.h>
DECLARE_GLOBAL_DATA_PTR;
/*
* struct gen_74x164_chip - Data for 74Hx164
*
* @oe: OE pin
* @nregs: number of registers
* @buffer: buffer for chained chips
*/
#define GEN_74X164_NUMBER_GPIOS 8
struct gen_74x164_priv {
struct gpio_desc oe;
u32 nregs;
/*
* Since the nregs are chained, every byte sent will make
* the previous byte shift to the next register in the
* chain. Thus, the first byte sent will end up in the last
* register at the end of the transfer. So, to have a logical
* numbering, store the bytes in reverse order.
*/
u8 *buffer;
};
static int gen_74x164_write_conf(struct udevice *dev)
{
struct gen_74x164_priv *priv = dev_get_priv(dev);
int ret;
ret = dm_spi_claim_bus(dev);
if (ret)
return ret;
ret = dm_spi_xfer(dev, priv->nregs * 8, priv->buffer, NULL,
SPI_XFER_BEGIN | SPI_XFER_END);
dm_spi_release_bus(dev);
return ret;
}
static int gen_74x164_get_value(struct udevice *dev, unsigned offset)
{
struct gen_74x164_priv *priv = dev_get_priv(dev);
uint bank = priv->nregs - 1 - offset / 8;
uint pin = offset % 8;
return (priv->buffer[bank] >> pin) & 0x1;
}
static int gen_74x164_set_value(struct udevice *dev, unsigned offset,
int value)
{
struct gen_74x164_priv *priv = dev_get_priv(dev);
uint bank = priv->nregs - 1 - offset / 8;
uint pin = offset % 8;
int ret;
if (value)
priv->buffer[bank] |= 1 << pin;
else
priv->buffer[bank] &= ~(1 << pin);
ret = gen_74x164_write_conf(dev);
if (ret)
return ret;
return 0;
}
static int gen_74x164_direction_input(struct udevice *dev, unsigned offset)
{
return -ENOSYS;
}
static int gen_74x164_direction_output(struct udevice *dev, unsigned offset,
int value)
{
return gen_74x164_set_value(dev, offset, value);
}
static int gen_74x164_get_function(struct udevice *dev, unsigned offset)
{
return GPIOF_OUTPUT;
}
static int gen_74x164_xlate(struct udevice *dev, struct gpio_desc *desc,
struct ofnode_phandle_args *args)
{
desc->offset = args->args[0];
desc->flags = args->args[1] & GPIO_ACTIVE_LOW ? GPIOD_ACTIVE_LOW : 0;
return 0;
}
static const struct dm_gpio_ops gen_74x164_ops = {
.direction_input = gen_74x164_direction_input,
.direction_output = gen_74x164_direction_output,
.get_value = gen_74x164_get_value,
.set_value = gen_74x164_set_value,
.get_function = gen_74x164_get_function,
.xlate = gen_74x164_xlate,
};
static int gen_74x164_probe(struct udevice *dev)
{
struct gen_74x164_priv *priv = dev_get_priv(dev);
struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
char *str, name[32];
int ret;
const void *fdt = gd->fdt_blob;
int node = dev_of_offset(dev);
snprintf(name, sizeof(name), "%s_", dev->name);
str = strdup(name);
if (!str)
return -ENOMEM;
/*
* See Linux kernel:
* Documentation/devicetree/bindings/gpio/gpio-74x164.txt
*/
priv->nregs = fdtdec_get_int(fdt, node, "registers-number", 1);
priv->buffer = calloc(priv->nregs, sizeof(u8));
if (!priv->buffer) {
ret = -ENOMEM;
goto free_str;
}
ret = fdtdec_get_byte_array(fdt, node, "registers-default",
priv->buffer, priv->nregs);
if (ret)
dev_dbg(dev, "No registers-default property\n");
ret = gpio_request_by_name(dev, "oe-gpios", 0, &priv->oe,
GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
if (ret) {
dev_dbg(dev, "No oe-pins property\n");
}
uc_priv->bank_name = str;
uc_priv->gpio_count = priv->nregs * 8;
ret = gen_74x164_write_conf(dev);
if (ret)
goto free_buf;
dev_dbg(dev, "%s is ready\n", dev->name);
return 0;
free_buf:
free(priv->buffer);
free_str:
free(str);
return ret;
}
static const struct udevice_id gen_74x164_ids[] = {
{ .compatible = "fairchild,74hc595" },
{ }
};
U_BOOT_DRIVER(74x164) = {
.name = "74x164",
.id = UCLASS_GPIO,
.ops = &gen_74x164_ops,
.probe = gen_74x164_probe,
.priv_auto_alloc_size = sizeof(struct gen_74x164_priv),
.of_match = gen_74x164_ids,
};