drivers/rtc: add support for Microchip MCP795
Add driver for SPI RTC Microchip MCP795. Only supports saving/loading time from the chip (i. e. no alarms/power events/ID). Signed-off-by: Josef Gajdusek <atx@atx.name> Cc: Jingoo Han <jg1.han@samsung.com> Acked-by: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Josef Gajdusek
Linus Torvalds
parent
10b06b87b7
commit
1fcbe42c1b
3 changed files with 208 additions and 0 deletions
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@ -661,6 +661,14 @@ config RTC_DRV_RX4581
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This driver can also be built as a module. If so the module
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will be called rtc-rx4581.
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config RTC_DRV_MCP795
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tristate "Microchip MCP795"
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help
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If you say yes here you will get support for the Microchip MCP795.
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This driver can also be built as a module. If so the module
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will be called rtc-mcp795.
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endif # SPI_MASTER
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comment "Platform RTC drivers"
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@ -81,6 +81,7 @@ obj-$(CONFIG_RTC_DRV_MAX8997) += rtc-max8997.o
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obj-$(CONFIG_RTC_DRV_MAX6902) += rtc-max6902.o
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obj-$(CONFIG_RTC_DRV_MAX77686) += rtc-max77686.o
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obj-$(CONFIG_RTC_DRV_MC13XXX) += rtc-mc13xxx.o
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obj-$(CONFIG_RTC_DRV_MCP795) += rtc-mcp795.o
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obj-$(CONFIG_RTC_DRV_MSM6242) += rtc-msm6242.o
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obj-$(CONFIG_RTC_DRV_MPC5121) += rtc-mpc5121.o
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obj-$(CONFIG_RTC_DRV_MV) += rtc-mv.o
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199
drivers/rtc/rtc-mcp795.c
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199
drivers/rtc/rtc-mcp795.c
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@ -0,0 +1,199 @@
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/*
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* SPI Driver for Microchip MCP795 RTC
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*
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* Copyright (C) Josef Gajdusek <atx@atx.name>
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*
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* based on other Linux RTC drivers
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*
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* Device datasheet:
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* http://ww1.microchip.com/downloads/en/DeviceDoc/22280A.pdf
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* */
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/device.h>
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#include <linux/printk.h>
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#include <linux/spi/spi.h>
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#include <linux/rtc.h>
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/* MCP795 Instructions, see datasheet table 3-1 */
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#define MCP795_EEREAD 0x03
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#define MCP795_EEWRITE 0x02
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#define MCP795_EEWRDI 0x04
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#define MCP795_EEWREN 0x06
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#define MCP795_SRREAD 0x05
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#define MCP795_SRWRITE 0x01
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#define MCP795_READ 0x13
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#define MCP795_WRITE 0x12
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#define MCP795_UNLOCK 0x14
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#define MCP795_IDWRITE 0x32
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#define MCP795_IDREAD 0x33
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#define MCP795_CLRWDT 0x44
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#define MCP795_CLRRAM 0x54
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#define MCP795_ST_BIT 0x80
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#define MCP795_24_BIT 0x40
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static int mcp795_rtcc_read(struct device *dev, u8 addr, u8 *buf, u8 count)
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{
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struct spi_device *spi = to_spi_device(dev);
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int ret;
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u8 tx[2];
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tx[0] = MCP795_READ;
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tx[1] = addr;
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ret = spi_write_then_read(spi, tx, sizeof(tx), buf, count);
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if (ret)
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dev_err(dev, "Failed reading %d bytes from address %x.\n",
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count, addr);
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return ret;
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}
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static int mcp795_rtcc_write(struct device *dev, u8 addr, u8 *data, u8 count)
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{
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struct spi_device *spi = to_spi_device(dev);
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int ret;
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u8 tx[2 + count];
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tx[0] = MCP795_WRITE;
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tx[1] = addr;
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memcpy(&tx[2], data, count);
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ret = spi_write(spi, tx, 2 + count);
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if (ret)
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dev_err(dev, "Failed to write %d bytes to address %x.\n",
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count, addr);
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return ret;
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}
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static int mcp795_rtcc_set_bits(struct device *dev, u8 addr, u8 mask, u8 state)
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{
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int ret;
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u8 tmp;
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ret = mcp795_rtcc_read(dev, addr, &tmp, 1);
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if (ret)
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return ret;
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if ((tmp & mask) != state) {
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tmp = (tmp & ~mask) | state;
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ret = mcp795_rtcc_write(dev, addr, &tmp, 1);
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}
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return ret;
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}
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static int mcp795_set_time(struct device *dev, struct rtc_time *tim)
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{
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int ret;
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u8 data[7];
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/* Read first, so we can leave config bits untouched */
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ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));
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if (ret)
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return ret;
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data[0] = (data[0] & 0x80) | ((tim->tm_sec / 10) << 4) | (tim->tm_sec % 10);
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data[1] = (data[1] & 0x80) | ((tim->tm_min / 10) << 4) | (tim->tm_min % 10);
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data[2] = ((tim->tm_hour / 10) << 4) | (tim->tm_hour % 10);
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data[4] = ((tim->tm_mday / 10) << 4) | ((tim->tm_mday) % 10);
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data[5] = (data[5] & 0x10) | (tim->tm_mon / 10) | (tim->tm_mon % 10);
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if (tim->tm_year > 100)
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tim->tm_year -= 100;
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data[6] = ((tim->tm_year / 10) << 4) | (tim->tm_year % 10);
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ret = mcp795_rtcc_write(dev, 0x01, data, sizeof(data));
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if (ret)
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return ret;
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dev_dbg(dev, "Set mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
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tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
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tim->tm_hour, tim->tm_min, tim->tm_sec);
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return 0;
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}
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static int mcp795_read_time(struct device *dev, struct rtc_time *tim)
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{
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int ret;
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u8 data[7];
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ret = mcp795_rtcc_read(dev, 0x01, data, sizeof(data));
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if (ret)
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return ret;
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tim->tm_sec = ((data[0] & 0x70) >> 4) * 10 + (data[0] & 0x0f);
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tim->tm_min = ((data[1] & 0x70) >> 4) * 10 + (data[1] & 0x0f);
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tim->tm_hour = ((data[2] & 0x30) >> 4) * 10 + (data[2] & 0x0f);
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tim->tm_mday = ((data[4] & 0x30) >> 4) * 10 + (data[4] & 0x0f);
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tim->tm_mon = ((data[5] & 0x10) >> 4) * 10 + (data[5] & 0x0f);
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tim->tm_year = ((data[6] & 0xf0) >> 4) * 10 + (data[6] & 0x0f) + 100; /* Assume we are in 20xx */
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dev_dbg(dev, "Read from mcp795: %04d-%02d-%02d %02d:%02d:%02d\n",
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tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
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tim->tm_hour, tim->tm_min, tim->tm_sec);
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return rtc_valid_tm(tim);
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}
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static struct rtc_class_ops mcp795_rtc_ops = {
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.read_time = mcp795_read_time,
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.set_time = mcp795_set_time
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};
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static int mcp795_probe(struct spi_device *spi)
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{
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struct rtc_device *rtc;
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int ret;
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spi->mode = SPI_MODE_0;
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spi->bits_per_word = 8;
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ret = spi_setup(spi);
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if (ret) {
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dev_err(&spi->dev, "Unable to setup SPI\n");
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return ret;
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}
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/* Start the oscillator */
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mcp795_rtcc_set_bits(&spi->dev, 0x01, MCP795_ST_BIT, MCP795_ST_BIT);
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/* Clear the 12 hour mode flag*/
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mcp795_rtcc_set_bits(&spi->dev, 0x03, MCP795_24_BIT, 0);
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rtc = devm_rtc_device_register(&spi->dev, "rtc-mcp795",
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&mcp795_rtc_ops, THIS_MODULE);
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if (IS_ERR(rtc))
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return PTR_ERR(rtc);
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spi_set_drvdata(spi, rtc);
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return 0;
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}
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static struct spi_driver mcp795_driver = {
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.driver = {
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.name = "rtc-mcp795",
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.owner = THIS_MODULE,
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},
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.probe = mcp795_probe,
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};
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module_spi_driver(mcp795_driver);
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MODULE_DESCRIPTION("MCP795 RTC SPI Driver");
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MODULE_AUTHOR("Josef Gajdusek <atx@atx.name>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("spi:mcp795");
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