diff options
Diffstat (limited to 'drivers/rtc/rtc-ds2404.c')
| -rw-r--r-- | drivers/rtc/rtc-ds2404.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds2404.c b/drivers/rtc/rtc-ds2404.c new file mode 100644 index 000000000..0480f5923 --- /dev/null +++ b/drivers/rtc/rtc-ds2404.c @@ -0,0 +1,256 @@ +// 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 = devm_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"); |