drivers/rtc/rtc-m48t86.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * ST M48T86 / Dallas DS12887 RTC driver
  * Copyright (c) 2006 Tower Technologies
  *
  * Author: Alessandro Zummo <a.zummo@towertech.it>
  *
  * This drivers only supports the clock running in BCD and 24H mode.
  * If it will be ever adapted to binary and 12H mode, care must be taken
  * to not introduce bugs.
  */

 #include <linux/module.h>
 #include <linux/rtc.h>
 #include <linux/platform_device.h>
 #include <linux/bcd.h>
 #include <linux/io.h>

 #define M48T86_SEC		0x00
 #define M48T86_SECALRM		0x01
 #define M48T86_MIN		0x02
 #define M48T86_MINALRM		0x03
 #define M48T86_HOUR		0x04
 #define M48T86_HOURALRM		0x05
 #define M48T86_DOW		0x06 /* 1 = sunday */
 #define M48T86_DOM		0x07
 #define M48T86_MONTH		0x08 /* 1 - 12 */
 #define M48T86_YEAR		0x09 /* 0 - 99 */
 #define M48T86_A		0x0a
 #define M48T86_B		0x0b
 #define M48T86_B_SET		BIT(7)
 #define M48T86_B_DM		BIT(2)
 #define M48T86_B_H24		BIT(1)
 #define M48T86_C		0x0c
 #define M48T86_D		0x0d
 #define M48T86_D_VRT		BIT(7)
 #define M48T86_NVRAM(x)		(0x0e + (x))
 #define M48T86_NVRAM_LEN	114

 struct m48t86_rtc_info {
 	void __iomem *index_reg;
 	void __iomem *data_reg;
 	struct rtc_device *rtc;
 };

 static unsigned char m48t86_readb(struct device *dev, unsigned long addr)
 {
 	struct m48t86_rtc_info *info = dev_get_drvdata(dev);
 	unsigned char value;

 	writeb(addr, info->index_reg);
 	value = readb(info->data_reg);

 	return value;
 }

 static void m48t86_writeb(struct device *dev,
 			  unsigned char value, unsigned long addr)
 {
 	struct m48t86_rtc_info *info = dev_get_drvdata(dev);

 	writeb(addr, info->index_reg);
 	writeb(value, info->data_reg);
 }

 static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	unsigned char reg;

 	reg = m48t86_readb(dev, M48T86_B);

 	if (reg & M48T86_B_DM) {
 		/* data (binary) mode */
 		tm->tm_sec	= m48t86_readb(dev, M48T86_SEC);
 		tm->tm_min	= m48t86_readb(dev, M48T86_MIN);
 		tm->tm_hour	= m48t86_readb(dev, M48T86_HOUR) & 0x3f;
 		tm->tm_mday	= m48t86_readb(dev, M48T86_DOM);
 		/* tm_mon is 0-11 */
 		tm->tm_mon	= m48t86_readb(dev, M48T86_MONTH) - 1;
 		tm->tm_year	= m48t86_readb(dev, M48T86_YEAR) + 100;
 		tm->tm_wday	= m48t86_readb(dev, M48T86_DOW);
 	} else {
 		/* bcd mode */
 		tm->tm_sec	= bcd2bin(m48t86_readb(dev, M48T86_SEC));
 		tm->tm_min	= bcd2bin(m48t86_readb(dev, M48T86_MIN));
 		tm->tm_hour	= bcd2bin(m48t86_readb(dev, M48T86_HOUR) &
 					  0x3f);
 		tm->tm_mday	= bcd2bin(m48t86_readb(dev, M48T86_DOM));
 		/* tm_mon is 0-11 */
 		tm->tm_mon	= bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1;
 		tm->tm_year	= bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100;
 		tm->tm_wday	= bcd2bin(m48t86_readb(dev, M48T86_DOW));
 	}

 	/* correct the hour if the clock is in 12h mode */
 	if (!(reg & M48T86_B_H24))
 		if (m48t86_readb(dev, M48T86_HOUR) & 0x80)
 			tm->tm_hour += 12;

 	return 0;
 }

 static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	unsigned char reg;

 	reg = m48t86_readb(dev, M48T86_B);

 	/* update flag and 24h mode */
 	reg |= M48T86_B_SET | M48T86_B_H24;
 	m48t86_writeb(dev, reg, M48T86_B);

 	if (reg & M48T86_B_DM) {
 		/* data (binary) mode */
 		m48t86_writeb(dev, tm->tm_sec, M48T86_SEC);
 		m48t86_writeb(dev, tm->tm_min, M48T86_MIN);
 		m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR);
 		m48t86_writeb(dev, tm->tm_mday, M48T86_DOM);
 		m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH);
 		m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR);
 		m48t86_writeb(dev, tm->tm_wday, M48T86_DOW);
 	} else {
 		/* bcd mode */
 		m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC);
 		m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN);
 		m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR);
 		m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM);
 		m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH);
 		m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR);
 		m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW);
 	}

 	/* update ended */
 	reg &= ~M48T86_B_SET;
 	m48t86_writeb(dev, reg, M48T86_B);

 	return 0;
 }

 static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
 {
 	unsigned char reg;

 	reg = m48t86_readb(dev, M48T86_B);

 	seq_printf(seq, "mode\t\t: %s\n",
 		   (reg & M48T86_B_DM) ? "binary" : "bcd");

 	reg = m48t86_readb(dev, M48T86_D);

 	seq_printf(seq, "battery\t\t: %s\n",
 		   (reg & M48T86_D_VRT) ? "ok" : "exhausted");

 	return 0;
 }

 static const struct rtc_class_ops m48t86_rtc_ops = {
 	.read_time	= m48t86_rtc_read_time,
 	.set_time	= m48t86_rtc_set_time,
 	.proc		= m48t86_rtc_proc,
 };

 static int m48t86_nvram_read(void *priv, unsigned int off, void *buf,
 			     size_t count)
 {
 	struct device *dev = priv;
 	unsigned int i;

 	for (i = 0; i < count; i++)
 		((u8 *)buf)[i] = m48t86_readb(dev, M48T86_NVRAM(off + i));

 	return 0;
 }

 static int m48t86_nvram_write(void *priv, unsigned int off, void *buf,
 			      size_t count)
 {
 	struct device *dev = priv;
 	unsigned int i;

 	for (i = 0; i < count; i++)
 		m48t86_writeb(dev, ((u8 *)buf)[i], M48T86_NVRAM(off + i));

 	return 0;
 }

 /*
  * The RTC is an optional feature at purchase time on some Technologic Systems
  * boards. Verify that it actually exists by checking if the last two bytes
  * of the NVRAM can be changed.
  *
  * This is based on the method used in their rtc7800.c example.
  */
 static bool m48t86_verify_chip(struct platform_device *pdev)
 {
 	unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2);
 	unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1);
 	unsigned char tmp0, tmp1;

 	tmp0 = m48t86_readb(&pdev->dev, offset0);
 	tmp1 = m48t86_readb(&pdev->dev, offset1);

 	m48t86_writeb(&pdev->dev, 0x00, offset0);
 	m48t86_writeb(&pdev->dev, 0x55, offset1);
 	if (m48t86_readb(&pdev->dev, offset1) == 0x55) {
 		m48t86_writeb(&pdev->dev, 0xaa, offset1);
 		if (m48t86_readb(&pdev->dev, offset1) == 0xaa &&
 		    m48t86_readb(&pdev->dev, offset0) == 0x00) {
 			m48t86_writeb(&pdev->dev, tmp0, offset0);
 			m48t86_writeb(&pdev->dev, tmp1, offset1);

 			return true;
 		}
 	}
 	return false;
 }

 static int m48t86_rtc_probe(struct platform_device *pdev)
 {
 	struct m48t86_rtc_info *info;
 	unsigned char reg;
 	int err;
 	struct nvmem_config m48t86_nvmem_cfg = {
 		.name = "m48t86_nvram",
 		.word_size = 1,
 		.stride = 1,
 		.size = M48T86_NVRAM_LEN,
 		.reg_read = m48t86_nvram_read,
 		.reg_write = m48t86_nvram_write,
 		.priv = &pdev->dev,
 	};

 	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return -ENOMEM;

 	info->index_reg = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(info->index_reg))
 		return PTR_ERR(info->index_reg);

 	info->data_reg = devm_platform_ioremap_resource(pdev, 1);
 	if (IS_ERR(info->data_reg))
 		return PTR_ERR(info->data_reg);

 	dev_set_drvdata(&pdev->dev, info);

 	if (!m48t86_verify_chip(pdev)) {
 		dev_info(&pdev->dev, "RTC not present\n");
 		return -ENODEV;
 	}

 	info->rtc = devm_rtc_allocate_device(&pdev->dev);
 	if (IS_ERR(info->rtc))
 		return PTR_ERR(info->rtc);

 	info->rtc->ops = &m48t86_rtc_ops;
 	info->rtc->nvram_old_abi = true;

 	err = rtc_register_device(info->rtc);
 	if (err)
 		return err;

 	rtc_nvmem_register(info->rtc, &m48t86_nvmem_cfg);

 	/* read battery status */
 	reg = m48t86_readb(&pdev->dev, M48T86_D);
 	dev_info(&pdev->dev, "battery %s\n",
 		 (reg & M48T86_D_VRT) ? "ok" : "exhausted");

 	return 0;
 }

 static struct platform_driver m48t86_rtc_platform_driver = {
 	.driver		= {
 		.name	= "rtc-m48t86",
 	},
 	.probe		= m48t86_rtc_probe,
 };

 module_platform_driver(m48t86_rtc_platform_driver);

 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 MODULE_DESCRIPTION("M48T86 RTC driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:rtc-m48t86");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* ST M48T86 / Dallas DS12887 RTC driver
	* Copyright (c) 2006 Tower Technologies
	*
	* Author: Alessandro Zummo <a.zummo@towertech.it>
	*
	* This drivers only supports the clock running in BCD and 24H mode.
	* If it will be ever adapted to binary and 12H mode, care must be taken
	* to not introduce bugs.
	*/

	#include <linux/module.h>
	#include <linux/rtc.h>
	#include <linux/platform_device.h>
	#include <linux/bcd.h>
	#include <linux/io.h>

	#define M48T86_SEC 0x00
	#define M48T86_SECALRM 0x01
	#define M48T86_MIN 0x02
	#define M48T86_MINALRM 0x03
	#define M48T86_HOUR 0x04
	#define M48T86_HOURALRM 0x05
	#define M48T86_DOW 0x06 /* 1 = sunday */
	#define M48T86_DOM 0x07
	#define M48T86_MONTH 0x08 /* 1 - 12 */
	#define M48T86_YEAR 0x09 /* 0 - 99 */
	#define M48T86_A 0x0a
	#define M48T86_B 0x0b
	#define M48T86_B_SET BIT(7)
	#define M48T86_B_DM BIT(2)
	#define M48T86_B_H24 BIT(1)
	#define M48T86_C 0x0c
	#define M48T86_D 0x0d
	#define M48T86_D_VRT BIT(7)
	#define M48T86_NVRAM(x) (0x0e + (x))
	#define M48T86_NVRAM_LEN 114

	struct m48t86_rtc_info {
	void __iomem *index_reg;
	void __iomem *data_reg;
	struct rtc_device *rtc;
	};

	static unsigned char m48t86_readb(struct device *dev, unsigned long addr)
	{
	struct m48t86_rtc_info *info = dev_get_drvdata(dev);
	unsigned char value;

	writeb(addr, info->index_reg);
	value = readb(info->data_reg);

	return value;
	}

	static void m48t86_writeb(struct device *dev,
	unsigned char value, unsigned long addr)
	{
	struct m48t86_rtc_info *info = dev_get_drvdata(dev);

	writeb(addr, info->index_reg);
	writeb(value, info->data_reg);
	}

	static int m48t86_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	unsigned char reg;

	reg = m48t86_readb(dev, M48T86_B);

	if (reg & M48T86_B_DM) {
	/* data (binary) mode */
	tm->tm_sec = m48t86_readb(dev, M48T86_SEC);
	tm->tm_min = m48t86_readb(dev, M48T86_MIN);
	tm->tm_hour = m48t86_readb(dev, M48T86_HOUR) & 0x3f;
	tm->tm_mday = m48t86_readb(dev, M48T86_DOM);
	/* tm_mon is 0-11 */
	tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1;
	tm->tm_year = m48t86_readb(dev, M48T86_YEAR) + 100;
	tm->tm_wday = m48t86_readb(dev, M48T86_DOW);
	} else {
	/* bcd mode */
	tm->tm_sec = bcd2bin(m48t86_readb(dev, M48T86_SEC));
	tm->tm_min = bcd2bin(m48t86_readb(dev, M48T86_MIN));
	tm->tm_hour = bcd2bin(m48t86_readb(dev, M48T86_HOUR) &
	0x3f);
	tm->tm_mday = bcd2bin(m48t86_readb(dev, M48T86_DOM));
	/* tm_mon is 0-11 */
	tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1;
	tm->tm_year = bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100;
	tm->tm_wday = bcd2bin(m48t86_readb(dev, M48T86_DOW));
	}

	/* correct the hour if the clock is in 12h mode */
	if (!(reg & M48T86_B_H24))
	if (m48t86_readb(dev, M48T86_HOUR) & 0x80)
	tm->tm_hour += 12;

	return 0;
	}

	static int m48t86_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	unsigned char reg;

	reg = m48t86_readb(dev, M48T86_B);

	/* update flag and 24h mode */
	reg \|= M48T86_B_SET \| M48T86_B_H24;
	m48t86_writeb(dev, reg, M48T86_B);

	if (reg & M48T86_B_DM) {
	/* data (binary) mode */
	m48t86_writeb(dev, tm->tm_sec, M48T86_SEC);
	m48t86_writeb(dev, tm->tm_min, M48T86_MIN);
	m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR);
	m48t86_writeb(dev, tm->tm_mday, M48T86_DOM);
	m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH);
	m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR);
	m48t86_writeb(dev, tm->tm_wday, M48T86_DOW);
	} else {
	/* bcd mode */
	m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC);
	m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN);
	m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR);
	m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM);
	m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH);
	m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR);
	m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW);
	}

	/* update ended */
	reg &= ~M48T86_B_SET;
	m48t86_writeb(dev, reg, M48T86_B);

	return 0;
	}

	static int m48t86_rtc_proc(struct device dev, struct seq_file seq)
	{
	unsigned char reg;

	reg = m48t86_readb(dev, M48T86_B);

	seq_printf(seq, "mode\t\t: %s\n",
	(reg & M48T86_B_DM) ? "binary" : "bcd");

	reg = m48t86_readb(dev, M48T86_D);

	seq_printf(seq, "battery\t\t: %s\n",
	(reg & M48T86_D_VRT) ? "ok" : "exhausted");

	return 0;
	}

	static const struct rtc_class_ops m48t86_rtc_ops = {
	.read_time = m48t86_rtc_read_time,
	.set_time = m48t86_rtc_set_time,
	.proc = m48t86_rtc_proc,
	};

	static int m48t86_nvram_read(void priv, unsigned int off, void buf,
	size_t count)
	{
	struct device *dev = priv;
	unsigned int i;

	for (i = 0; i < count; i++)
	((u8 *)buf)[i] = m48t86_readb(dev, M48T86_NVRAM(off + i));

	return 0;
	}

	static int m48t86_nvram_write(void priv, unsigned int off, void buf,
	size_t count)
	{
	struct device *dev = priv;
	unsigned int i;

	for (i = 0; i < count; i++)
	m48t86_writeb(dev, ((u8 *)buf)[i], M48T86_NVRAM(off + i));

	return 0;
	}

	/*
	* The RTC is an optional feature at purchase time on some Technologic Systems
	* boards. Verify that it actually exists by checking if the last two bytes
	* of the NVRAM can be changed.
	*
	* This is based on the method used in their rtc7800.c example.
	*/
	static bool m48t86_verify_chip(struct platform_device *pdev)
	{
	unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2);
	unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1);
	unsigned char tmp0, tmp1;

	tmp0 = m48t86_readb(&pdev->dev, offset0);
	tmp1 = m48t86_readb(&pdev->dev, offset1);

	m48t86_writeb(&pdev->dev, 0x00, offset0);
	m48t86_writeb(&pdev->dev, 0x55, offset1);
	if (m48t86_readb(&pdev->dev, offset1) == 0x55) {
	m48t86_writeb(&pdev->dev, 0xaa, offset1);
	if (m48t86_readb(&pdev->dev, offset1) == 0xaa &&
	m48t86_readb(&pdev->dev, offset0) == 0x00) {
	m48t86_writeb(&pdev->dev, tmp0, offset0);
	m48t86_writeb(&pdev->dev, tmp1, offset1);

	return true;
	}
	}
	return false;
	}

	static int m48t86_rtc_probe(struct platform_device *pdev)
	{
	struct m48t86_rtc_info *info;
	unsigned char reg;
	int err;
	struct nvmem_config m48t86_nvmem_cfg = {
	.name = "m48t86_nvram",
	.word_size = 1,
	.stride = 1,
	.size = M48T86_NVRAM_LEN,
	.reg_read = m48t86_nvram_read,
	.reg_write = m48t86_nvram_write,
	.priv = &pdev->dev,
	};

	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
	if (!info)
	return -ENOMEM;

	info->index_reg = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(info->index_reg))
	return PTR_ERR(info->index_reg);

	info->data_reg = devm_platform_ioremap_resource(pdev, 1);
	if (IS_ERR(info->data_reg))
	return PTR_ERR(info->data_reg);

	dev_set_drvdata(&pdev->dev, info);

	if (!m48t86_verify_chip(pdev)) {
	dev_info(&pdev->dev, "RTC not present\n");
	return -ENODEV;
	}

	info->rtc = devm_rtc_allocate_device(&pdev->dev);
	if (IS_ERR(info->rtc))
	return PTR_ERR(info->rtc);

	info->rtc->ops = &m48t86_rtc_ops;
	info->rtc->nvram_old_abi = true;

	err = rtc_register_device(info->rtc);
	if (err)
	return err;

	rtc_nvmem_register(info->rtc, &m48t86_nvmem_cfg);

	/* read battery status */
	reg = m48t86_readb(&pdev->dev, M48T86_D);
	dev_info(&pdev->dev, "battery %s\n",
	(reg & M48T86_D_VRT) ? "ok" : "exhausted");

	return 0;
	}

	static struct platform_driver m48t86_rtc_platform_driver = {
	.driver = {
	.name = "rtc-m48t86",
	},
	.probe = m48t86_rtc_probe,
	};

	module_platform_driver(m48t86_rtc_platform_driver);

	MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
	MODULE_DESCRIPTION("M48T86 RTC driver");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:rtc-m48t86");