linux/drivers/rtc/rtc-ds2404.c
Nicholas Mc Guire 8aec4b8750 rtc: ds2404: use hw endiannes variable
Converting from hardware to host endiannes was done using reassignment
to the same variable which makes sparse unhappy as it can not verify
the endiannes handling properly. To allow sparse to verify endiannes
handling an explicit __le32 is introduced. Note that this patch does
not change the generated binary (x86_64 and ppc64 binary diff).

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2019-05-23 17:42:25 +02:00

257 lines
5.8 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/platform_data/rtc-ds2404.h>
#include <linux/delay.h>
#include <linux/gpio.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_gpio {
const char *name;
unsigned int gpio;
};
struct ds2404 {
struct ds2404_gpio *gpio;
struct rtc_device *rtc;
};
static struct ds2404_gpio ds2404_gpio[] = {
{ "RTC RST", 0 },
{ "RTC CLK", 0 },
{ "RTC DQ", 0 },
};
static int ds2404_gpio_map(struct ds2404 *chip, struct platform_device *pdev,
struct ds2404_platform_data *pdata)
{
int i, err;
ds2404_gpio[DS2404_RST].gpio = pdata->gpio_rst;
ds2404_gpio[DS2404_CLK].gpio = pdata->gpio_clk;
ds2404_gpio[DS2404_DQ].gpio = pdata->gpio_dq;
for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++) {
err = gpio_request(ds2404_gpio[i].gpio, ds2404_gpio[i].name);
if (err) {
dev_err(&pdev->dev, "error mapping gpio %s: %d\n",
ds2404_gpio[i].name, err);
goto err_request;
}
if (i != DS2404_DQ)
gpio_direction_output(ds2404_gpio[i].gpio, 1);
}
chip->gpio = ds2404_gpio;
return 0;
err_request:
while (--i >= 0)
gpio_free(ds2404_gpio[i].gpio);
return err;
}
static void ds2404_gpio_unmap(void *data)
{
int i;
for (i = 0; i < ARRAY_SIZE(ds2404_gpio); i++)
gpio_free(ds2404_gpio[i].gpio);
}
static void ds2404_reset(struct device *dev)
{
gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 0);
udelay(1000);
gpio_set_value(ds2404_gpio[DS2404_RST].gpio, 1);
gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 0);
udelay(10);
}
static void ds2404_write_byte(struct device *dev, u8 byte)
{
int i;
gpio_direction_output(ds2404_gpio[DS2404_DQ].gpio, 1);
for (i = 0; i < 8; i++) {
gpio_set_value(ds2404_gpio[DS2404_DQ].gpio, byte & (1 << i));
udelay(10);
gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1);
udelay(10);
gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
udelay(10);
}
}
static u8 ds2404_read_byte(struct device *dev)
{
int i;
u8 ret = 0;
gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio);
for (i = 0; i < 8; i++) {
gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 0);
udelay(10);
if (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio))
ret |= 1 << i;
gpio_set_value(ds2404_gpio[DS2404_CLK].gpio, 1);
udelay(10);
}
return ret;
}
static void ds2404_read_memory(struct device *dev, u16 offset,
int length, u8 *out)
{
ds2404_reset(dev);
ds2404_write_byte(dev, DS2404_READ_MEMORY_CMD);
ds2404_write_byte(dev, offset & 0xff);
ds2404_write_byte(dev, (offset >> 8) & 0xff);
while (length--)
*out++ = ds2404_read_byte(dev);
}
static void ds2404_write_memory(struct device *dev, u16 offset,
int length, u8 *out)
{
int i;
u8 ta01, ta02, es;
ds2404_reset(dev);
ds2404_write_byte(dev, DS2404_WRITE_SCRATCHPAD_CMD);
ds2404_write_byte(dev, offset & 0xff);
ds2404_write_byte(dev, (offset >> 8) & 0xff);
for (i = 0; i < length; i++)
ds2404_write_byte(dev, out[i]);
ds2404_reset(dev);
ds2404_write_byte(dev, DS2404_READ_SCRATCHPAD_CMD);
ta01 = ds2404_read_byte(dev);
ta02 = ds2404_read_byte(dev);
es = ds2404_read_byte(dev);
for (i = 0; i < length; i++) {
if (out[i] != ds2404_read_byte(dev)) {
dev_err(dev, "read invalid data\n");
return;
}
}
ds2404_reset(dev);
ds2404_write_byte(dev, DS2404_COPY_SCRATCHPAD_CMD);
ds2404_write_byte(dev, ta01);
ds2404_write_byte(dev, ta02);
ds2404_write_byte(dev, es);
gpio_direction_input(ds2404_gpio[DS2404_DQ].gpio);
while (gpio_get_value(ds2404_gpio[DS2404_DQ].gpio))
;
}
static void ds2404_enable_osc(struct device *dev)
{
u8 in[1] = { 0x10 }; /* enable oscillator */
ds2404_write_memory(dev, 0x201, 1, in);
}
static int ds2404_read_time(struct device *dev, struct rtc_time *dt)
{
unsigned long time = 0;
__le32 hw_time = 0;
ds2404_read_memory(dev, 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)
{
u32 time = cpu_to_le32(rtc_tm_to_time64(dt));
ds2404_write_memory(dev, 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_platform_data *pdata = dev_get_platdata(&pdev->dev);
struct ds2404 *chip;
int retval = -EBUSY;
chip = devm_kzalloc(&pdev->dev, sizeof(struct ds2404), GFP_KERNEL);
if (!chip)
return -ENOMEM;
chip->rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(chip->rtc))
return PTR_ERR(chip->rtc);
retval = ds2404_gpio_map(chip, pdev, pdata);
if (retval)
return retval;
retval = devm_add_action_or_reset(&pdev->dev, ds2404_gpio_unmap, chip);
if (retval)
return retval;
dev_info(&pdev->dev, "using GPIOs RST:%d, CLK:%d, DQ:%d\n",
chip->gpio[DS2404_RST].gpio, chip->gpio[DS2404_CLK].gpio,
chip->gpio[DS2404_DQ].gpio);
platform_set_drvdata(pdev, chip);
chip->rtc->ops = &ds2404_rtc_ops;
chip->rtc->range_max = U32_MAX;
retval = rtc_register_device(chip->rtc);
if (retval)
return retval;
ds2404_enable_osc(&pdev->dev);
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");