rtc: driver for Conexant Digicolor CX92755 on-chip RTC
Add driver for the RTC hardware block on the Conexant CX92755 SoC, from
the Digicolor series of SoCs. Tested on the Equinox evaluation board for
the CX92755 chip.
[akpm@linux-foundation.org: build command arrays at compile-time]
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/rtc-digicolor.c b/drivers/rtc/rtc-digicolor.c
new file mode 100644
index 0000000..8d05596
--- /dev/null
+++ b/drivers/rtc/rtc-digicolor.c
@@ -0,0 +1,227 @@
+/*
+ * Real Time Clock driver for Conexant Digicolor
+ *
+ * Copyright (C) 2015 Paradox Innovation Ltd.
+ *
+ * Author: Baruch Siach <baruch@tkos.co.il>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/of.h>
+
+#define DC_RTC_CONTROL 0x0
+#define DC_RTC_TIME 0x8
+#define DC_RTC_REFERENCE 0xc
+#define DC_RTC_ALARM 0x10
+#define DC_RTC_INTFLAG_CLEAR 0x14
+#define DC_RTC_INTENABLE 0x16
+
+#define DC_RTC_CMD_MASK 0xf
+#define DC_RTC_GO_BUSY BIT(7)
+
+#define CMD_NOP 0
+#define CMD_RESET 1
+#define CMD_WRITE 3
+#define CMD_READ 4
+
+#define CMD_DELAY_US (10*1000)
+#define CMD_TIMEOUT_US (500*CMD_DELAY_US)
+
+struct dc_rtc {
+ struct rtc_device *rtc_dev;
+ void __iomem *regs;
+};
+
+static int dc_rtc_cmds(struct dc_rtc *rtc, const u8 *cmds, int len)
+{
+ u8 val;
+ int i, ret;
+
+ for (i = 0; i < len; i++) {
+ writeb_relaxed((cmds[i] & DC_RTC_CMD_MASK) | DC_RTC_GO_BUSY,
+ rtc->regs + DC_RTC_CONTROL);
+ ret = readb_relaxed_poll_timeout(
+ rtc->regs + DC_RTC_CONTROL, val,
+ !(val & DC_RTC_GO_BUSY), CMD_DELAY_US, CMD_TIMEOUT_US);
+ if (ret < 0)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int dc_rtc_read(struct dc_rtc *rtc, unsigned long *val)
+{
+ static const u8 read_cmds[] = {CMD_READ, CMD_NOP};
+ u32 reference, time1, time2;
+ int ret;
+
+ ret = dc_rtc_cmds(rtc, read_cmds, ARRAY_SIZE(read_cmds));
+ if (ret < 0)
+ return ret;
+
+ reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
+ time1 = readl_relaxed(rtc->regs + DC_RTC_TIME);
+ /* Read twice to ensure consistency */
+ while (1) {
+ time2 = readl_relaxed(rtc->regs + DC_RTC_TIME);
+ if (time1 == time2)
+ break;
+ time1 = time2;
+ }
+
+ *val = reference + time1;
+ return 0;
+}
+
+static int dc_rtc_write(struct dc_rtc *rtc, u32 val)
+{
+ static const u8 write_cmds[] = {CMD_WRITE, CMD_NOP, CMD_RESET, CMD_NOP};
+
+ writel_relaxed(val, rtc->regs + DC_RTC_REFERENCE);
+ return dc_rtc_cmds(rtc, write_cmds, ARRAY_SIZE(write_cmds));
+}
+
+static int dc_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct dc_rtc *rtc = dev_get_drvdata(dev);
+ unsigned long now;
+ int ret;
+
+ ret = dc_rtc_read(rtc, &now);
+ if (ret < 0)
+ return ret;
+ rtc_time64_to_tm(now, tm);
+
+ return 0;
+}
+
+static int dc_rtc_set_mmss(struct device *dev, unsigned long secs)
+{
+ struct dc_rtc *rtc = dev_get_drvdata(dev);
+
+ return dc_rtc_write(rtc, secs);
+}
+
+static int dc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ struct dc_rtc *rtc = dev_get_drvdata(dev);
+ u32 alarm_reg, reference;
+ unsigned long now;
+ int ret;
+
+ alarm_reg = readl_relaxed(rtc->regs + DC_RTC_ALARM);
+ reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
+ rtc_time64_to_tm(reference + alarm_reg, &alarm->time);
+
+ ret = dc_rtc_read(rtc, &now);
+ if (ret < 0)
+ return ret;
+
+ alarm->pending = alarm_reg + reference > now;
+ alarm->enabled = readl_relaxed(rtc->regs + DC_RTC_INTENABLE);
+
+ return 0;
+}
+
+static int dc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ struct dc_rtc *rtc = dev_get_drvdata(dev);
+ time64_t alarm_time;
+ u32 reference;
+
+ alarm_time = rtc_tm_to_time64(&alarm->time);
+
+ reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
+ writel_relaxed(alarm_time - reference, rtc->regs + DC_RTC_ALARM);
+
+ writeb_relaxed(!!alarm->enabled, rtc->regs + DC_RTC_INTENABLE);
+
+ return 0;
+}
+
+static int dc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+ struct dc_rtc *rtc = dev_get_drvdata(dev);
+
+ writeb_relaxed(!!enabled, rtc->regs + DC_RTC_INTENABLE);
+
+ return 0;
+}
+
+static struct rtc_class_ops dc_rtc_ops = {
+ .read_time = dc_rtc_read_time,
+ .set_mmss = dc_rtc_set_mmss,
+ .read_alarm = dc_rtc_read_alarm,
+ .set_alarm = dc_rtc_set_alarm,
+ .alarm_irq_enable = dc_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t dc_rtc_irq(int irq, void *dev_id)
+{
+ struct dc_rtc *rtc = dev_id;
+
+ writeb_relaxed(1, rtc->regs + DC_RTC_INTFLAG_CLEAR);
+ rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);
+
+ return IRQ_HANDLED;
+}
+
+static int __init dc_rtc_probe(struct platform_device *pdev)
+{
+ struct resource *res;
+ struct dc_rtc *rtc;
+ int irq, ret;
+
+ rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+ if (!rtc)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ rtc->regs = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(rtc->regs))
+ return PTR_ERR(rtc->regs);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return irq;
+ ret = devm_request_irq(&pdev->dev, irq, dc_rtc_irq, 0, pdev->name, rtc);
+ if (ret < 0)
+ return ret;
+
+ platform_set_drvdata(pdev, rtc);
+ rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
+ &dc_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc->rtc_dev))
+ return PTR_ERR(rtc->rtc_dev);
+
+ return 0;
+}
+
+static const struct of_device_id dc_dt_ids[] = {
+ { .compatible = "cnxt,cx92755-rtc" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, dc_dt_ids);
+
+static struct platform_driver dc_rtc_driver = {
+ .driver = {
+ .name = "digicolor_rtc",
+ .of_match_table = of_match_ptr(dc_dt_ids),
+ },
+};
+module_platform_driver_probe(dc_rtc_driver, dc_rtc_probe);
+
+MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
+MODULE_DESCRIPTION("Conexant Digicolor Realtime Clock Driver (RTC)");
+MODULE_LICENSE("GPL");