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/Kconfig b/drivers/rtc/Kconfig
index b5b5c3d..faeee2d 100644 (file)
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1111,6 +1111,16 @@ config RTC_DRV_DAVINCI
          This driver can also be built as a module. If so, the module
          will be called rtc-davinci.
 
+config RTC_DRV_DIGICOLOR
+       tristate "Conexant Digicolor RTC"
+       depends on ARCH_DIGICOLOR
+       help
+         If you say yes here you get support for the RTC on Conexant
+         Digicolor platforms. This currently includes the CX92755 SoC.
+
+         This driver can also be built as a module. If so, the module
+         will be called rtc-digicolor.
+
 config RTC_DRV_IMXDI
        tristate "Freescale IMX DryIce Real Time Clock"
        depends on ARCH_MXC

diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 69c8706..c31731c 100644 (file)
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_RTC_DRV_DA9052)  += rtc-da9052.o
 obj-$(CONFIG_RTC_DRV_DA9055)   += rtc-da9055.o
 obj-$(CONFIG_RTC_DRV_DA9063)   += rtc-da9063.o
 obj-$(CONFIG_RTC_DRV_DAVINCI)  += rtc-davinci.o
+obj-$(CONFIG_RTC_DRV_DIGICOLOR)        += rtc-digicolor.o
 obj-$(CONFIG_RTC_DRV_DM355EVM) += rtc-dm355evm.o
 obj-$(CONFIG_RTC_DRV_VRTC)     += rtc-mrst.o
 obj-$(CONFIG_RTC_DRV_DS1216)   += rtc-ds1216.o

diff --git a/drivers/rtc/rtc-digicolor.c b/drivers/rtc/rtc-digicolor.c
new file mode 100644 (file)
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");