linux/drivers/rtc/rtc-ds2404.c
Linus Walleij d890cfc25f rtc: ds2404: Convert to GPIO descriptors
This converts the DS2404 to use GPIO descriptors instead of
hard-coded global GPIO numbers.

The platform data can be deleted because there are no in-tree
users and it only contained GPIO numbers which are now
passed using descriptor tables (or device tree or ACPI).

The driver was rewritten to use a state container for the
device driver state (struct ds2404 *chip) and pass that
around instead of using a global singleton storage for the
GPIO handles.

When declaring GPIO descriptor tables or other hardware
descriptions for the RTC driver, implementers should take care
to flag the RESET line as active low, such as by using the
GPIOD_ACTIVE_LOW flag in the descriptor table.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230807-descriptors-rtc-v1-1-ce0f9187576e@linaro.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2023-08-17 00:55:56 +02:00

226 lines
5.0 KiB
C

// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2012 Sven Schnelle <svens@stackframe.org>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/types.h>
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/slab.h>
#include <linux/io.h>
#define DS2404_STATUS_REG 0x200
#define DS2404_CONTROL_REG 0x201
#define DS2404_RTC_REG 0x202
#define DS2404_WRITE_SCRATCHPAD_CMD 0x0f
#define DS2404_READ_SCRATCHPAD_CMD 0xaa
#define DS2404_COPY_SCRATCHPAD_CMD 0x55
#define DS2404_READ_MEMORY_CMD 0xf0
#define DS2404_RST 0
#define DS2404_CLK 1
#define DS2404_DQ 2
struct ds2404 {
struct device *dev;
struct gpio_desc *rst_gpiod;
struct gpio_desc *clk_gpiod;
struct gpio_desc *dq_gpiod;
struct rtc_device *rtc;
};
static int ds2404_gpio_map(struct ds2404 *chip, struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
/* This will de-assert RESET, declare this GPIO as GPIOD_ACTIVE_LOW */
chip->rst_gpiod = devm_gpiod_get(dev, "rst", GPIOD_OUT_LOW);
if (IS_ERR(chip->rst_gpiod))
return PTR_ERR(chip->rst_gpiod);
chip->clk_gpiod = devm_gpiod_get(dev, "clk", GPIOD_OUT_HIGH);
if (IS_ERR(chip->clk_gpiod))
return PTR_ERR(chip->clk_gpiod);
chip->dq_gpiod = devm_gpiod_get(dev, "dq", GPIOD_ASIS);
if (IS_ERR(chip->dq_gpiod))
return PTR_ERR(chip->dq_gpiod);
return 0;
}
static void ds2404_reset(struct ds2404 *chip)
{
gpiod_set_value(chip->rst_gpiod, 1);
udelay(1000);
gpiod_set_value(chip->rst_gpiod, 0);
gpiod_set_value(chip->clk_gpiod, 0);
gpiod_direction_output(chip->dq_gpiod, 0);
udelay(10);
}
static void ds2404_write_byte(struct ds2404 *chip, u8 byte)
{
int i;
gpiod_direction_output(chip->dq_gpiod, 1);
for (i = 0; i < 8; i++) {
gpiod_set_value(chip->dq_gpiod, byte & (1 << i));
udelay(10);
gpiod_set_value(chip->clk_gpiod, 1);
udelay(10);
gpiod_set_value(chip->clk_gpiod, 0);
udelay(10);
}
}
static u8 ds2404_read_byte(struct ds2404 *chip)
{
int i;
u8 ret = 0;
gpiod_direction_input(chip->dq_gpiod);
for (i = 0; i < 8; i++) {
gpiod_set_value(chip->clk_gpiod, 0);
udelay(10);
if (gpiod_get_value(chip->dq_gpiod))
ret |= 1 << i;
gpiod_set_value(chip->clk_gpiod, 1);
udelay(10);
}
return ret;
}
static void ds2404_read_memory(struct ds2404 *chip, u16 offset,
int length, u8 *out)
{
ds2404_reset(chip);
ds2404_write_byte(chip, DS2404_READ_MEMORY_CMD);
ds2404_write_byte(chip, offset & 0xff);
ds2404_write_byte(chip, (offset >> 8) & 0xff);
while (length--)
*out++ = ds2404_read_byte(chip);
}
static void ds2404_write_memory(struct ds2404 *chip, u16 offset,
int length, u8 *out)
{
int i;
u8 ta01, ta02, es;
ds2404_reset(chip);
ds2404_write_byte(chip, DS2404_WRITE_SCRATCHPAD_CMD);
ds2404_write_byte(chip, offset & 0xff);
ds2404_write_byte(chip, (offset >> 8) & 0xff);
for (i = 0; i < length; i++)
ds2404_write_byte(chip, out[i]);
ds2404_reset(chip);
ds2404_write_byte(chip, DS2404_READ_SCRATCHPAD_CMD);
ta01 = ds2404_read_byte(chip);
ta02 = ds2404_read_byte(chip);
es = ds2404_read_byte(chip);
for (i = 0; i < length; i++) {
if (out[i] != ds2404_read_byte(chip)) {
dev_err(chip->dev, "read invalid data\n");
return;
}
}
ds2404_reset(chip);
ds2404_write_byte(chip, DS2404_COPY_SCRATCHPAD_CMD);
ds2404_write_byte(chip, ta01);
ds2404_write_byte(chip, ta02);
ds2404_write_byte(chip, es);
while (gpiod_get_value(chip->dq_gpiod))
;
}
static void ds2404_enable_osc(struct ds2404 *chip)
{
u8 in[1] = { 0x10 }; /* enable oscillator */
ds2404_write_memory(chip, 0x201, 1, in);
}
static int ds2404_read_time(struct device *dev, struct rtc_time *dt)
{
struct ds2404 *chip = dev_get_drvdata(dev);
unsigned long time = 0;
__le32 hw_time = 0;
ds2404_read_memory(chip, 0x203, 4, (u8 *)&hw_time);
time = le32_to_cpu(hw_time);
rtc_time64_to_tm(time, dt);
return 0;
}
static int ds2404_set_time(struct device *dev, struct rtc_time *dt)
{
struct ds2404 *chip = dev_get_drvdata(dev);
u32 time = cpu_to_le32(rtc_tm_to_time64(dt));
ds2404_write_memory(chip, 0x203, 4, (u8 *)&time);
return 0;
}
static const struct rtc_class_ops ds2404_rtc_ops = {
.read_time = ds2404_read_time,
.set_time = ds2404_set_time,
};
static int rtc_probe(struct platform_device *pdev)
{
struct ds2404 *chip;
int retval = -EBUSY;
chip = devm_kzalloc(&pdev->dev, sizeof(struct ds2404), GFP_KERNEL);
if (!chip)
return -ENOMEM;
chip->dev = &pdev->dev;
chip->rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(chip->rtc))
return PTR_ERR(chip->rtc);
retval = ds2404_gpio_map(chip, pdev);
if (retval)
return retval;
platform_set_drvdata(pdev, chip);
chip->rtc->ops = &ds2404_rtc_ops;
chip->rtc->range_max = U32_MAX;
retval = devm_rtc_register_device(chip->rtc);
if (retval)
return retval;
ds2404_enable_osc(chip);
return 0;
}
static struct platform_driver rtc_device_driver = {
.probe = rtc_probe,
.driver = {
.name = "ds2404",
},
};
module_platform_driver(rtc_device_driver);
MODULE_DESCRIPTION("DS2404 RTC");
MODULE_AUTHOR("Sven Schnelle");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ds2404");