diff options
Diffstat (limited to 'target/linux/mvebu/patches-4.14/420-rtc-armada38x-add-support-for-trimming-the-RTC.patch')
| -rw-r--r-- | target/linux/mvebu/patches-4.14/420-rtc-armada38x-add-support-for-trimming-the-RTC.patch | 143 |
1 files changed, 0 insertions, 143 deletions
diff --git a/target/linux/mvebu/patches-4.14/420-rtc-armada38x-add-support-for-trimming-the-RTC.patch b/target/linux/mvebu/patches-4.14/420-rtc-armada38x-add-support-for-trimming-the-RTC.patch deleted file mode 100644 index 2974a69760..0000000000 --- a/target/linux/mvebu/patches-4.14/420-rtc-armada38x-add-support-for-trimming-the-RTC.patch +++ /dev/null @@ -1,143 +0,0 @@ -commit f94ffbc2c2a4128c4412bb483d0807722dfb682b -Author: Russell King <rmk+kernel@armlinux.org.uk> -Date: Fri Sep 29 11:23:31 2017 +0100 - - rtc: armada38x: add support for trimming the RTC - - Add support for trimming the RTC using the offset mechanism. This RTC - supports two modes: low update mode and high update mode. Low update - mode has finer precision than high update mode, so we use the low mode - where possible. - - Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> - Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> - ---- a/drivers/rtc/rtc-armada38x.c -+++ b/drivers/rtc/rtc-armada38x.c -@@ -28,6 +28,8 @@ - #define RTC_IRQ_AL_EN BIT(0) - #define RTC_IRQ_FREQ_EN BIT(1) - #define RTC_IRQ_FREQ_1HZ BIT(2) -+#define RTC_CCR 0x18 -+#define RTC_CCR_MODE BIT(15) - - #define RTC_TIME 0xC - #define RTC_ALARM1 0x10 -@@ -343,18 +345,117 @@ static irqreturn_t armada38x_rtc_alarm_i - return IRQ_HANDLED; - } - -+/* -+ * The information given in the Armada 388 functional spec is complex. -+ * They give two different formulas for calculating the offset value, -+ * but when considering "Offset" as an 8-bit signed integer, they both -+ * reduce down to (we shall rename "Offset" as "val" here): -+ * -+ * val = (f_ideal / f_measured - 1) / resolution where f_ideal = 32768 -+ * -+ * Converting to time, f = 1/t: -+ * val = (t_measured / t_ideal - 1) / resolution where t_ideal = 1/32768 -+ * -+ * => t_measured / t_ideal = val * resolution + 1 -+ * -+ * "offset" in the RTC interface is defined as: -+ * t = t0 * (1 + offset * 1e-9) -+ * where t is the desired period, t0 is the measured period with a zero -+ * offset, which is t_measured above. With t0 = t_measured and t = t_ideal, -+ * offset = (t_ideal / t_measured - 1) / 1e-9 -+ * -+ * => t_ideal / t_measured = offset * 1e-9 + 1 -+ * -+ * so: -+ * -+ * offset * 1e-9 + 1 = 1 / (val * resolution + 1) -+ * -+ * We want "resolution" to be an integer, so resolution = R * 1e-9, giving -+ * offset = 1e18 / (val * R + 1e9) - 1e9 -+ * val = (1e18 / (offset + 1e9) - 1e9) / R -+ * with a common transformation: -+ * f(x) = 1e18 / (x + 1e9) - 1e9 -+ * offset = f(val * R) -+ * val = f(offset) / R -+ * -+ * Armada 38x supports two modes, fine mode (954ppb) and coarse mode (3815ppb). -+ */ -+static long armada38x_ppb_convert(long ppb) -+{ -+ long div = ppb + 1000000000L; -+ -+ return div_s64(1000000000000000000LL + div / 2, div) - 1000000000L; -+} -+ -+static int armada38x_rtc_read_offset(struct device *dev, long *offset) -+{ -+ struct armada38x_rtc *rtc = dev_get_drvdata(dev); -+ unsigned long ccr, flags; -+ long ppb_cor; -+ -+ spin_lock_irqsave(&rtc->lock, flags); -+ ccr = rtc->data->read_rtc_reg(rtc, RTC_CCR); -+ spin_unlock_irqrestore(&rtc->lock, flags); -+ -+ ppb_cor = (ccr & RTC_CCR_MODE ? 3815 : 954) * (s8)ccr; -+ /* ppb_cor + 1000000000L can never be zero */ -+ *offset = armada38x_ppb_convert(ppb_cor); -+ -+ return 0; -+} -+ -+static int armada38x_rtc_set_offset(struct device *dev, long offset) -+{ -+ struct armada38x_rtc *rtc = dev_get_drvdata(dev); -+ unsigned long ccr = 0; -+ long ppb_cor, off; -+ -+ /* -+ * The maximum ppb_cor is -128 * 3815 .. 127 * 3815, but we -+ * need to clamp the input. This equates to -484270 .. 488558. -+ * Not only is this to stop out of range "off" but also to -+ * avoid the division by zero in armada38x_ppb_convert(). -+ */ -+ offset = clamp(offset, -484270L, 488558L); -+ -+ ppb_cor = armada38x_ppb_convert(offset); -+ -+ /* -+ * Use low update mode where possible, which gives a better -+ * resolution of correction. -+ */ -+ off = DIV_ROUND_CLOSEST(ppb_cor, 954); -+ if (off > 127 || off < -128) { -+ ccr = RTC_CCR_MODE; -+ off = DIV_ROUND_CLOSEST(ppb_cor, 3815); -+ } -+ -+ /* -+ * Armada 388 requires a bit pattern in bits 14..8 depending on -+ * the sign bit: { 0, ~S, S, S, S, S, S } -+ */ -+ ccr |= (off & 0x3fff) ^ 0x2000; -+ rtc_delayed_write(ccr, rtc, RTC_CCR); -+ -+ return 0; -+} -+ - static const struct rtc_class_ops armada38x_rtc_ops = { - .read_time = armada38x_rtc_read_time, - .set_time = armada38x_rtc_set_time, - .read_alarm = armada38x_rtc_read_alarm, - .set_alarm = armada38x_rtc_set_alarm, - .alarm_irq_enable = armada38x_rtc_alarm_irq_enable, -+ .read_offset = armada38x_rtc_read_offset, -+ .set_offset = armada38x_rtc_set_offset, - }; - - static const struct rtc_class_ops armada38x_rtc_ops_noirq = { - .read_time = armada38x_rtc_read_time, - .set_time = armada38x_rtc_set_time, - .read_alarm = armada38x_rtc_read_alarm, -+ .read_offset = armada38x_rtc_read_offset, -+ .set_offset = armada38x_rtc_set_offset, - }; - - static const struct armada38x_rtc_data armada38x_data = { |