Add support for reading RTC clock from device tree using clock framework also update the default calibration value to 0x7FFF as per RTC specifications.
Falls back to 'calibration' property if clock unavailable, and uses default calibration if neither is present. Only writes calibration when hardware register reads zero. The calibration write previously in zynqmp_rtc_set() has been moved to the probe function. The earlier implementation wrote calibration on every time update to clear the tick counter, but since calibration is now dynamically configured from clock framework or device tree during probe, it only requires one-time initialization. This avoids repeated tick counter resets and unnecessary overhead. Signed-off-by: Pranav Tilak <[email protected]> --- Changes in v3: - Reorder includes alphabetically - Update the commit message Changes in v2: - Rename variable from clk_freq to calibval - Handle case where clock node exists but has no clock-frequency property - Treat invalid clock frequency as error instead of warning - Move calibration validation outside if-else to apply to all code paths drivers/rtc/zynqmp_rtc.c | 64 +++++++++++++++++++++++++++------------- 1 file changed, 44 insertions(+), 20 deletions(-) diff --git a/drivers/rtc/zynqmp_rtc.c b/drivers/rtc/zynqmp_rtc.c index 15122a04838..4fee75bf9cf 100644 --- a/drivers/rtc/zynqmp_rtc.c +++ b/drivers/rtc/zynqmp_rtc.c @@ -5,26 +5,30 @@ #define LOG_CATEGORY UCLASS_RTC +#include <clk.h> #include <dm.h> #include <rtc.h> #include <asm/io.h> +#include <dm/device_compat.h> /* RTC Registers */ #define RTC_SET_TM_WR 0x00 #define RTC_SET_TM_RD 0x04 #define RTC_CALIB_WR 0x08 +#define RTC_CALIB_RD 0x0C #define RTC_CUR_TM 0x10 #define RTC_INT_STS 0x20 #define RTC_CTRL 0x40 #define RTC_INT_SEC BIT(0) #define RTC_BATT_EN BIT(31) -#define RTC_CALIB_DEF 0x198233 +#define RTC_CALIB_DEF 0x7FFF +#define RTC_FREQ_MAX 0x10000 #define RTC_CALIB_MASK 0x1FFFFF struct zynqmp_rtc_priv { fdt_addr_t base; - unsigned int calibval; + unsigned long calibval; }; static int zynqmp_rtc_get(struct udevice *dev, struct rtc_time *tm) @@ -70,13 +74,6 @@ static int zynqmp_rtc_set(struct udevice *dev, const struct rtc_time *tm) */ new_time = rtc_mktime(tm) + 1; - /* - * Writing into calibration register will clear the Tick Counter and - * force the next second to be signaled exactly in 1 second period - */ - priv->calibval &= RTC_CALIB_MASK; - writel(priv->calibval, (priv->base + RTC_CALIB_WR)); - writel(new_time, priv->base + RTC_SET_TM_WR); /* @@ -107,15 +104,6 @@ static int zynqmp_rtc_init(struct udevice *dev) rtc_ctrl |= RTC_BATT_EN; writel(rtc_ctrl, priv->base + RTC_CTRL); - /* - * Based on crystal freq of 33.330 KHz - * set the seconds counter and enable, set fractions counter - * to default value suggested as per design spec - * to correct RTC delay in frequency over period of time. - */ - priv->calibval &= RTC_CALIB_MASK; - writel(priv->calibval, (priv->base + RTC_CALIB_WR)); - return 0; } @@ -128,8 +116,44 @@ static int zynqmp_rtc_probe(struct udevice *dev) if (priv->base == FDT_ADDR_T_NONE) return -EINVAL; - priv->calibval = dev_read_u32_default(dev, "calibration", - RTC_CALIB_DEF); + ret = readl(priv->base + RTC_CALIB_RD); + if (!ret) { + struct clk rtc_clk; + unsigned long clk_rate; + + /* Get the RTC clock rate */ + ret = clk_get_by_name_optional(dev, "rtc", &rtc_clk); + if (!ret) { + clk_rate = clk_get_rate(&rtc_clk); + /* Use clock frequency if valid, fallback to calibration value */ + if (clk_rate > 0 && clk_rate <= RTC_FREQ_MAX) { + /* Valid clock frequency */ + priv->calibval = clk_rate - 1; + } else if (clk_rate == 0) { + priv->calibval = dev_read_u32_default(dev, "calibration", + RTC_CALIB_DEF); + } else { + dev_err(dev, "Invalid clock frequency 0x%lx\n", + clk_rate); + return -EINVAL; + } + } else { + /* Clock framework unavailable, use DT calibration */ + priv->calibval = dev_read_u32_default(dev, "calibration", + RTC_CALIB_DEF); + } + + /* Validate final calibration value */ + if (priv->calibval > RTC_FREQ_MAX) { + dev_err(dev, "Invalid calibration 0x%lx\n", + priv->calibval); + return -EINVAL; + } + + writel(priv->calibval, (priv->base + RTC_CALIB_WR)); + } else { + priv->calibval = ret & RTC_CALIB_MASK; + } ret = zynqmp_rtc_init(dev); -- 2.34.1
