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284 lines
7.4 KiB
284 lines
7.4 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* ST M48T86 / Dallas DS12887 RTC driver |
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* Copyright (c) 2006 Tower Technologies |
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* |
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* Author: Alessandro Zummo <[email protected]> |
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* |
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* This drivers only supports the clock running in BCD and 24H mode. |
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* If it will be ever adapted to binary and 12H mode, care must be taken |
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* to not introduce bugs. |
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*/ |
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#include <linux/module.h> |
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#include <linux/rtc.h> |
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#include <linux/platform_device.h> |
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#include <linux/bcd.h> |
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#include <linux/io.h> |
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#define M48T86_SEC 0x00 |
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#define M48T86_SECALRM 0x01 |
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#define M48T86_MIN 0x02 |
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#define M48T86_MINALRM 0x03 |
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#define M48T86_HOUR 0x04 |
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#define M48T86_HOURALRM 0x05 |
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#define M48T86_DOW 0x06 /* 1 = sunday */ |
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#define M48T86_DOM 0x07 |
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#define M48T86_MONTH 0x08 /* 1 - 12 */ |
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#define M48T86_YEAR 0x09 /* 0 - 99 */ |
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#define M48T86_A 0x0a |
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#define M48T86_B 0x0b |
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#define M48T86_B_SET BIT(7) |
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#define M48T86_B_DM BIT(2) |
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#define M48T86_B_H24 BIT(1) |
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#define M48T86_C 0x0c |
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#define M48T86_D 0x0d |
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#define M48T86_D_VRT BIT(7) |
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#define M48T86_NVRAM(x) (0x0e + (x)) |
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#define M48T86_NVRAM_LEN 114 |
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struct m48t86_rtc_info { |
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void __iomem *index_reg; |
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void __iomem *data_reg; |
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struct rtc_device *rtc; |
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}; |
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static unsigned char m48t86_readb(struct device *dev, unsigned long addr) |
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{ |
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struct m48t86_rtc_info *info = dev_get_drvdata(dev); |
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unsigned char value; |
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writeb(addr, info->index_reg); |
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value = readb(info->data_reg); |
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return value; |
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} |
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static void m48t86_writeb(struct device *dev, |
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unsigned char value, unsigned long addr) |
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{ |
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struct m48t86_rtc_info *info = dev_get_drvdata(dev); |
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writeb(addr, info->index_reg); |
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writeb(value, info->data_reg); |
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} |
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static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm) |
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{ |
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unsigned char reg; |
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reg = m48t86_readb(dev, M48T86_B); |
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if (reg & M48T86_B_DM) { |
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/* data (binary) mode */ |
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tm->tm_sec = m48t86_readb(dev, M48T86_SEC); |
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tm->tm_min = m48t86_readb(dev, M48T86_MIN); |
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tm->tm_hour = m48t86_readb(dev, M48T86_HOUR) & 0x3f; |
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tm->tm_mday = m48t86_readb(dev, M48T86_DOM); |
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/* tm_mon is 0-11 */ |
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tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1; |
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tm->tm_year = m48t86_readb(dev, M48T86_YEAR) + 100; |
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tm->tm_wday = m48t86_readb(dev, M48T86_DOW); |
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} else { |
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/* bcd mode */ |
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tm->tm_sec = bcd2bin(m48t86_readb(dev, M48T86_SEC)); |
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tm->tm_min = bcd2bin(m48t86_readb(dev, M48T86_MIN)); |
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tm->tm_hour = bcd2bin(m48t86_readb(dev, M48T86_HOUR) & |
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0x3f); |
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tm->tm_mday = bcd2bin(m48t86_readb(dev, M48T86_DOM)); |
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/* tm_mon is 0-11 */ |
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tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1; |
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tm->tm_year = bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100; |
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tm->tm_wday = bcd2bin(m48t86_readb(dev, M48T86_DOW)); |
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} |
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/* correct the hour if the clock is in 12h mode */ |
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if (!(reg & M48T86_B_H24)) |
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if (m48t86_readb(dev, M48T86_HOUR) & 0x80) |
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tm->tm_hour += 12; |
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return 0; |
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} |
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static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm) |
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{ |
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unsigned char reg; |
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reg = m48t86_readb(dev, M48T86_B); |
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/* update flag and 24h mode */ |
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reg |= M48T86_B_SET | M48T86_B_H24; |
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m48t86_writeb(dev, reg, M48T86_B); |
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if (reg & M48T86_B_DM) { |
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/* data (binary) mode */ |
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m48t86_writeb(dev, tm->tm_sec, M48T86_SEC); |
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m48t86_writeb(dev, tm->tm_min, M48T86_MIN); |
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m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR); |
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m48t86_writeb(dev, tm->tm_mday, M48T86_DOM); |
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m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH); |
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m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR); |
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m48t86_writeb(dev, tm->tm_wday, M48T86_DOW); |
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} else { |
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/* bcd mode */ |
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m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC); |
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m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN); |
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m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR); |
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m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM); |
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m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH); |
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m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR); |
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m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW); |
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} |
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/* update ended */ |
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reg &= ~M48T86_B_SET; |
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m48t86_writeb(dev, reg, M48T86_B); |
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return 0; |
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} |
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static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq) |
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{ |
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unsigned char reg; |
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reg = m48t86_readb(dev, M48T86_B); |
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seq_printf(seq, "mode\t\t: %s\n", |
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(reg & M48T86_B_DM) ? "binary" : "bcd"); |
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reg = m48t86_readb(dev, M48T86_D); |
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seq_printf(seq, "battery\t\t: %s\n", |
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(reg & M48T86_D_VRT) ? "ok" : "exhausted"); |
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return 0; |
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} |
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static const struct rtc_class_ops m48t86_rtc_ops = { |
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.read_time = m48t86_rtc_read_time, |
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.set_time = m48t86_rtc_set_time, |
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.proc = m48t86_rtc_proc, |
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}; |
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static int m48t86_nvram_read(void *priv, unsigned int off, void *buf, |
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size_t count) |
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{ |
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struct device *dev = priv; |
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unsigned int i; |
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for (i = 0; i < count; i++) |
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((u8 *)buf)[i] = m48t86_readb(dev, M48T86_NVRAM(off + i)); |
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return 0; |
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} |
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static int m48t86_nvram_write(void *priv, unsigned int off, void *buf, |
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size_t count) |
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{ |
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struct device *dev = priv; |
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unsigned int i; |
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for (i = 0; i < count; i++) |
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m48t86_writeb(dev, ((u8 *)buf)[i], M48T86_NVRAM(off + i)); |
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return 0; |
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} |
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/* |
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* The RTC is an optional feature at purchase time on some Technologic Systems |
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* boards. Verify that it actually exists by checking if the last two bytes |
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* of the NVRAM can be changed. |
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* |
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* This is based on the method used in their rtc7800.c example. |
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*/ |
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static bool m48t86_verify_chip(struct platform_device *pdev) |
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{ |
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unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2); |
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unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1); |
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unsigned char tmp0, tmp1; |
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tmp0 = m48t86_readb(&pdev->dev, offset0); |
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tmp1 = m48t86_readb(&pdev->dev, offset1); |
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m48t86_writeb(&pdev->dev, 0x00, offset0); |
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m48t86_writeb(&pdev->dev, 0x55, offset1); |
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if (m48t86_readb(&pdev->dev, offset1) == 0x55) { |
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m48t86_writeb(&pdev->dev, 0xaa, offset1); |
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if (m48t86_readb(&pdev->dev, offset1) == 0xaa && |
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m48t86_readb(&pdev->dev, offset0) == 0x00) { |
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m48t86_writeb(&pdev->dev, tmp0, offset0); |
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m48t86_writeb(&pdev->dev, tmp1, offset1); |
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return true; |
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} |
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} |
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return false; |
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} |
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static int m48t86_rtc_probe(struct platform_device *pdev) |
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{ |
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struct m48t86_rtc_info *info; |
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unsigned char reg; |
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int err; |
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struct nvmem_config m48t86_nvmem_cfg = { |
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.name = "m48t86_nvram", |
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.word_size = 1, |
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.stride = 1, |
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.size = M48T86_NVRAM_LEN, |
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.reg_read = m48t86_nvram_read, |
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.reg_write = m48t86_nvram_write, |
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.priv = &pdev->dev, |
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}; |
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info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL); |
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if (!info) |
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return -ENOMEM; |
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info->index_reg = devm_platform_ioremap_resource(pdev, 0); |
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if (IS_ERR(info->index_reg)) |
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return PTR_ERR(info->index_reg); |
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info->data_reg = devm_platform_ioremap_resource(pdev, 1); |
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if (IS_ERR(info->data_reg)) |
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return PTR_ERR(info->data_reg); |
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dev_set_drvdata(&pdev->dev, info); |
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if (!m48t86_verify_chip(pdev)) { |
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dev_info(&pdev->dev, "RTC not present\n"); |
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return -ENODEV; |
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} |
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info->rtc = devm_rtc_allocate_device(&pdev->dev); |
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if (IS_ERR(info->rtc)) |
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return PTR_ERR(info->rtc); |
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info->rtc->ops = &m48t86_rtc_ops; |
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err = devm_rtc_register_device(info->rtc); |
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if (err) |
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return err; |
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devm_rtc_nvmem_register(info->rtc, &m48t86_nvmem_cfg); |
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/* read battery status */ |
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reg = m48t86_readb(&pdev->dev, M48T86_D); |
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dev_info(&pdev->dev, "battery %s\n", |
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(reg & M48T86_D_VRT) ? "ok" : "exhausted"); |
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return 0; |
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} |
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static struct platform_driver m48t86_rtc_platform_driver = { |
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.driver = { |
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.name = "rtc-m48t86", |
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}, |
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.probe = m48t86_rtc_probe, |
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}; |
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module_platform_driver(m48t86_rtc_platform_driver); |
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MODULE_AUTHOR("Alessandro Zummo <[email protected]>"); |
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MODULE_DESCRIPTION("M48T86 RTC driver"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("platform:rtc-m48t86");
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