forked from mirrors/linux
184a182ed5
Read and writes the time to the non-battery backed RTC in the ASPEED BMC system on chip families. Signed-off-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
136 lines
3.2 KiB
C
136 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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// Copyright 2015 IBM Corp.
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/rtc.h>
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#include <linux/io.h>
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struct aspeed_rtc {
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struct rtc_device *rtc_dev;
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void __iomem *base;
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};
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#define RTC_TIME 0x00
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#define RTC_YEAR 0x04
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#define RTC_CTRL 0x10
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#define RTC_UNLOCK BIT(1)
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#define RTC_ENABLE BIT(0)
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static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct aspeed_rtc *rtc = dev_get_drvdata(dev);
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unsigned int cent, year;
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u32 reg1, reg2;
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if (!(readl(rtc->base + RTC_CTRL) & RTC_ENABLE)) {
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dev_dbg(dev, "%s failing as rtc disabled\n", __func__);
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return -EINVAL;
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}
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do {
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reg2 = readl(rtc->base + RTC_YEAR);
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reg1 = readl(rtc->base + RTC_TIME);
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} while (reg2 != readl(rtc->base + RTC_YEAR));
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tm->tm_mday = (reg1 >> 24) & 0x1f;
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tm->tm_hour = (reg1 >> 16) & 0x1f;
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tm->tm_min = (reg1 >> 8) & 0x3f;
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tm->tm_sec = (reg1 >> 0) & 0x3f;
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cent = (reg2 >> 16) & 0x1f;
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year = (reg2 >> 8) & 0x7f;
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tm->tm_mon = ((reg2 >> 0) & 0x0f) - 1;
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tm->tm_year = year + (cent * 100) - 1900;
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dev_dbg(dev, "%s %ptR", __func__, tm);
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return 0;
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}
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static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct aspeed_rtc *rtc = dev_get_drvdata(dev);
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u32 reg1, reg2, ctrl;
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int year, cent;
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cent = (tm->tm_year + 1900) / 100;
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year = tm->tm_year % 100;
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reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) |
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tm->tm_sec;
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reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) |
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((tm->tm_mon + 1) & 0xf);
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ctrl = readl(rtc->base + RTC_CTRL);
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writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL);
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writel(reg1, rtc->base + RTC_TIME);
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writel(reg2, rtc->base + RTC_YEAR);
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/* Re-lock and ensure enable is set now that a time is programmed */
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writel(ctrl | RTC_ENABLE, rtc->base + RTC_CTRL);
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return 0;
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}
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static const struct rtc_class_ops aspeed_rtc_ops = {
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.read_time = aspeed_rtc_read_time,
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.set_time = aspeed_rtc_set_time,
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};
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static int aspeed_rtc_probe(struct platform_device *pdev)
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{
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struct aspeed_rtc *rtc;
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struct resource *res;
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int ret;
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rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
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if (!rtc)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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rtc->base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(rtc->base))
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return PTR_ERR(rtc->base);
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rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
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if (IS_ERR(rtc->rtc_dev))
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return PTR_ERR(rtc->rtc_dev);
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platform_set_drvdata(pdev, rtc);
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rtc->rtc_dev->ops = &aspeed_rtc_ops;
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rtc->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
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rtc->rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */
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ret = rtc_register_device(rtc->rtc_dev);
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if (ret)
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return ret;
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return 0;
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}
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static const struct of_device_id aspeed_rtc_match[] = {
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{ .compatible = "aspeed,ast2400-rtc", },
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{ .compatible = "aspeed,ast2500-rtc", },
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{ .compatible = "aspeed,ast2600-rtc", },
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{}
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};
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MODULE_DEVICE_TABLE(of, aspeed_rtc_match);
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static struct platform_driver aspeed_rtc_driver = {
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.driver = {
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.name = "aspeed-rtc",
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.of_match_table = of_match_ptr(aspeed_rtc_match),
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},
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};
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module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe);
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MODULE_DESCRIPTION("ASPEED RTC driver");
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MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
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MODULE_LICENSE("GPL");
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