@@ -21,6 +21,7 @@
#include <linux/module.h>
#include <linux/io.h>
#include <linux/init.h>
+#include <linux/clk.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/rtc.h>
@@ -53,18 +54,31 @@
#define STMP3XXX_RTC_PERSISTENT0 0x60
#define STMP3XXX_RTC_PERSISTENT0_SET 0x64
#define STMP3XXX_RTC_PERSISTENT0_CLR 0x68
+#define STMP3XXX_RTC_PERSISTENT0_CLOCKSOURCE (1 << 0)
#define STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN 0x00000002
#define STMP3XXX_RTC_PERSISTENT0_ALARM_EN 0x00000004
+#define STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP (1 << 4)
+#define STMP3XXX_RTC_PERSISTENT0_XTAL32KHZ_PWRUP (1 << 5)
+#define STMP3XXX_RTC_PERSISTENT0_XTAL32_FREQ (1 << 6)
+
#define STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE 0x00000080
#define STMP3XXX_RTC_PERSISTENT1 0x70
/* missing bitmask in headers */
#define STMP3XXX_RTC_PERSISTENT1_FORCE_UPDATER 0x80000000
+enum clock_source {
+ MXS_UNKNOWN,
+ MXS_OSC_24M,
+ MXS_OSC_32K,
+ MXS_OSC_32K768
+};
+
struct stmp3xxx_rtc_data {
struct rtc_device *rtc;
void __iomem *io;
int irq_alarm;
+ enum clock_source clk_src;
};
#if IS_ENABLED(CONFIG_STMP3XXX_RTC_WATCHDOG)
@@ -168,11 +182,55 @@ static irqreturn_t stmp3xxx_rtc_interrupt(int irq, void *dev_id)
return IRQ_NONE;
}
+/*
+ * To keep the energy consumption low, keep only
+ * the really used oscillator running when the power is down
+ */
+static void stmp3xxx_alarm_keep_oscillator(const struct stmp3xxx_rtc_data *rtc_data)
+{
+ switch (rtc_data->clk_src) {
+ case MXS_OSC_24M:
+ /* keep the 24 MHz oscillator running even in power down */
+ writel(STMP3XXX_RTC_PERSISTENT0_XTAL32_FREQ | /* 24 MHz / 750 */
+ STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP,
+ rtc_data->io + STMP3XXX_RTC_PERSISTENT0_SET);
+ writel(STMP3XXX_RTC_PERSISTENT0_XTAL32KHZ_PWRUP |
+ STMP3XXX_RTC_PERSISTENT0_CLOCKSOURCE,
+ rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
+ break;
+ case MXS_OSC_32K:
+ /* keep the 32 kHz oscillator running even in power down */
+ writel(STMP3XXX_RTC_PERSISTENT0_XTAL32_FREQ | /* 32 kHz */
+ STMP3XXX_RTC_PERSISTENT0_XTAL32KHZ_PWRUP |
+ STMP3XXX_RTC_PERSISTENT0_CLOCKSOURCE,
+ rtc_data->io + STMP3XXX_RTC_PERSISTENT0_SET);
+ writel(STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP,
+ rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
+ break;
+ case MXS_OSC_32K768:
+ /* keep the 32 kHz oscillator running even in power down */
+ writel(STMP3XXX_RTC_PERSISTENT0_XTAL32KHZ_PWRUP |
+ STMP3XXX_RTC_PERSISTENT0_CLOCKSOURCE,
+ rtc_data->io + STMP3XXX_RTC_PERSISTENT0_SET);
+ writel(STMP3XXX_RTC_PERSISTENT0_XTAL32_FREQ | /* 32.768 kHz */
+ STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP,
+ rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
+ break;
+ case MXS_UNKNOWN:
+ default:
+ break;
+ }
+}
+
static int stmp3xxx_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);
+ stmp3xxx_alarm_keep_oscillator(rtc_data);
+
if (enabled) {
+ writel(STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE, /* to be able to sleep */
+ rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
writel(STMP3XXX_RTC_PERSISTENT0_ALARM_EN |
STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN,
rtc_data->io + STMP3XXX_RTC_PERSISTENT0_SET);
@@ -240,6 +298,8 @@ static int stmp3xxx_rtc_probe(struct platform_device *pdev)
{
struct stmp3xxx_rtc_data *rtc_data;
struct resource *r;
+ struct clk *clk;
+ unsigned long rate;
int err;
rtc_data = kzalloc(sizeof *rtc_data, GFP_KERNEL);
@@ -272,6 +332,35 @@ static int stmp3xxx_rtc_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, rtc_data);
mxs_reset_block(rtc_data->io);
+
+ /*
+ * configure the RTC to provide the correct time
+ */
+ clk = devm_clk_get(&pdev->dev, "32k");
+ if (IS_ERR(clk)) {
+ /* just a fall back */
+ dev_warn(&pdev->dev, "RTC's input clock undefined\n");
+ rtc_data->clk_src = MXS_OSC_24M;
+ } else {
+ rate = clk_get_rate(clk);
+ if (rate == 0) {
+ /* no dedicated external crystal */
+ rtc_data->clk_src = MXS_OSC_24M;
+ dev_info(&pdev->dev, "Using 24 MHz as RTC's clock\n");
+ } else if (rate == 32000) {
+ rtc_data->clk_src = MXS_OSC_32K;
+ dev_info(&pdev->dev, "Using 32.0 kHz as RTC's clock\n");
+ } else if (rate == 32768) {
+ rtc_data->clk_src = MXS_OSC_32K768;
+ dev_info(&pdev->dev, "Using 32.768 kHz as RTC's clock\n");
+ } else
+ dev_warn(&pdev->dev,
+ "Cannot init the RTC's clock source\n");
+ }
+
+ /* basically configure the RTC's input clock */
+ stmp3xxx_alarm_keep_oscillator(rtc_data);
+
writel(STMP3XXX_RTC_PERSISTENT0_ALARM_EN |
STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN |
STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE,