--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Holtek HT1380/HT1381 Serial Timekeeper Chip
+ *
+ * Communication with the chip is vendor-specific.
+ * It is done via 3 GPIO pins: reset, clock, and data.
+ * Describe in .dts this way:
+ *
+ * rtc {
+ * compatible = "holtek,ht1380";
+ * rst-gpios = <&gpio 19 GPIO_ACTIVE_LOW>;
+ * clk-gpios = <&gpio 20 GPIO_ACTIVE_HIGH>;
+ * dat-gpios = <&gpio 21 GPIO_ACTIVE_HIGH>;
+ * };
+ *
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <rtc.h>
+#include <bcd.h>
+#include <asm/gpio.h>
+#include <linux/delay.h>
+
+struct ht1380_priv {
+ struct gpio_desc rst_desc;
+ struct gpio_desc clk_desc;
+ struct gpio_desc dat_desc;
+};
+
+enum registers {
+ SEC,
+ MIN,
+ HOUR,
+ MDAY,
+ MONTH,
+ WDAY,
+ YEAR,
+ WP,
+ N_REGS
+};
+
+enum hour_mode {
+ AMPM_MODE = 0x80, /* RTC is in AM/PM mode */
+ PM_NOW = 0x20, /* set if PM, clear if AM */
+};
+
+static const int BURST = 0xbe;
+static const int READ = 1;
+
+static void ht1380_half_period_delay(void)
+{
+ /*
+ * Delay for half a period. 1 us complies with the 500 KHz maximum
+ * input serial clock limit given by the datasheet.
+ */
+ udelay(1);
+}
+
+static int ht1380_send_byte(struct ht1380_priv *priv, int byte)
+{
+ int ret;
+
+ for (int bit = 0; bit < 8; bit++) {
+ ret = dm_gpio_set_value(&priv->dat_desc, byte >> bit & 1);
+ if (ret)
+ break;
+ ht1380_half_period_delay();
+
+ ret = dm_gpio_set_value(&priv->clk_desc, 1);
+ if (ret)
+ break;
+ ht1380_half_period_delay();
+
+ ret = dm_gpio_set_value(&priv->clk_desc, 0);
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+
+/*
+ * Leave reset state. The transfer operation can then be started.
+ */
+static int ht1380_reset_off(struct ht1380_priv *priv)
+{
+ const unsigned int T_CC = 4; /* us, Reset to Clock Setup */
+ int ret;
+
+ /*
+ * Leave RESET state.
+ * Make sure we make the minimal delay required by the datasheet.
+ */
+ ret = dm_gpio_set_value(&priv->rst_desc, 0);
+ udelay(T_CC);
+
+ return ret;
+}
+
+/*
+ * Enter reset state. Completes the transfer operation.
+ */
+static int ht1380_reset_on(struct ht1380_priv *priv)
+{
+ const unsigned int T_CWH = 4; /* us, Reset Inactive Time */
+ int ret;
+
+ /*
+ * Enter RESET state.
+ * Make sure we make the minimal delay required by the datasheet.
+ */
+ ret = dm_gpio_set_value(&priv->rst_desc, 1);
+ udelay(T_CWH);
+
+ return ret;
+}
+
+static int ht1380_rtc_get(struct udevice *dev, struct rtc_time *tm)
+{
+ struct ht1380_priv *priv = dev_get_priv(dev);
+ int ret, i, bit, reg[N_REGS];
+
+ ret = dm_gpio_set_value(&priv->clk_desc, 0);
+ if (ret)
+ return ret;
+
+ ret = dm_gpio_set_dir_flags(&priv->dat_desc, GPIOD_IS_OUT);
+ if (ret)
+ return ret;
+
+ ret = ht1380_reset_off(priv);
+ if (ret)
+ goto exit;
+
+ ret = ht1380_send_byte(priv, BURST + READ);
+ if (ret)
+ goto exit;
+
+ ret = dm_gpio_set_dir_flags(&priv->dat_desc, GPIOD_IS_IN);
+ if (ret)
+ goto exit;
+
+ for (i = 0; i < N_REGS; i++) {
+ reg[i] = 0;
+
+ for (bit = 0; bit < 8; bit++) {
+ ht1380_half_period_delay();
+
+ ret = dm_gpio_set_value(&priv->clk_desc, 1);
+ if (ret)
+ goto exit;
+ ht1380_half_period_delay();
+
+ reg[i] |= dm_gpio_get_value(&priv->dat_desc) << bit;
+ ret = dm_gpio_set_value(&priv->clk_desc, 0);
+ if (ret)
+ goto exit;
+ }
+ }
+
+ ret = -EINVAL;
+
+ /* Correctness check: some bits are always zero */
+ if (reg[MIN] & 0x80 || reg[HOUR] & 0x40 || reg[MDAY] & 0xc0 ||
+ reg[MONTH] & 0xe0 || reg[WDAY] & 0xf8 || reg[WP] & 0x7f)
+ goto exit;
+
+ /* Correctness check: some registers are always non-zero */
+ if (!reg[MDAY] || !reg[MONTH] || !reg[WDAY])
+ goto exit;
+
+ tm->tm_sec = bcd2bin(reg[SEC]);
+ tm->tm_min = bcd2bin(reg[MIN]);
+ if (reg[HOUR] & AMPM_MODE) {
+ /* AM-PM Mode, range is 01-12 */
+ tm->tm_hour = bcd2bin(reg[HOUR] & 0x1f) % 12;
+ if (reg[HOUR] & PM_NOW) {
+ /* it is PM (otherwise AM) */
+ tm->tm_hour += 12;
+ }
+ } else {
+ /* 24-hour Mode, range is 0-23 */
+ tm->tm_hour = bcd2bin(reg[HOUR]);
+ }
+ tm->tm_mday = bcd2bin(reg[MDAY]);
+ tm->tm_mon = bcd2bin(reg[MONTH]);
+ tm->tm_year = 2000 + bcd2bin(reg[YEAR]);
+ tm->tm_wday = bcd2bin(reg[WDAY]) - 1;
+ tm->tm_yday = 0;
+ tm->tm_isdst = 0;
+
+ ret = 0;
+
+exit:
+ ht1380_reset_on(priv);
+
+ return ret;
+}
+
+static int ht1380_write_protection_off(struct ht1380_priv *priv)
+{
+ int ret;
+ const int PROTECT = 0x8e;
+
+ ret = ht1380_reset_off(priv);
+ if (ret)
+ return ret;
+
+ ret = ht1380_send_byte(priv, PROTECT);
+ if (ret)
+ return ret;
+ ret = ht1380_send_byte(priv, 0); /* WP bit is 0 */
+ if (ret)
+ return ret;
+
+ return ht1380_reset_on(priv);
+}
+
+static int ht1380_rtc_set(struct udevice *dev, const struct rtc_time *tm)
+{
+ struct ht1380_priv *priv = dev_get_priv(dev);
+ int ret, i, reg[N_REGS];
+
+ ret = dm_gpio_set_value(&priv->clk_desc, 0);
+ if (ret)
+ return ret;
+
+ ret = dm_gpio_set_dir_flags(&priv->dat_desc, GPIOD_IS_OUT);
+ if (ret)
+ goto exit;
+
+ ret = ht1380_write_protection_off(priv);
+ if (ret)
+ goto exit;
+
+ reg[SEC] = bin2bcd(tm->tm_sec);
+ reg[MIN] = bin2bcd(tm->tm_min);
+ reg[HOUR] = bin2bcd(tm->tm_hour);
+ reg[MDAY] = bin2bcd(tm->tm_mday);
+ reg[MONTH] = bin2bcd(tm->tm_mon);
+ reg[WDAY] = bin2bcd(tm->tm_wday) + 1;
+ reg[YEAR] = bin2bcd(tm->tm_year - 2000);
+ reg[WP] = 0x80; /* WP bit is 1 */
+
+ ret = ht1380_reset_off(priv);
+ if (ret)
+ goto exit;
+
+ ret = ht1380_send_byte(priv, BURST);
+ for (i = 0; i < N_REGS && ret; i++)
+ ret = ht1380_send_byte(priv, reg[i]);
+
+exit:
+ ht1380_reset_on(priv);
+
+ return ret;
+}
+
+static int ht1380_probe(struct udevice *dev)
+{
+ int ret;
+ struct ht1380_priv *priv;
+
+ priv = dev_get_priv(dev);
+ if (!priv)
+ return -EINVAL;
+
+ ret = gpio_request_by_name(dev, "rst-gpios", 0,
+ &priv->rst_desc, GPIOD_IS_OUT);
+ if (ret)
+ goto fail_rst;
+
+ ret = gpio_request_by_name(dev, "clk-gpios", 0,
+ &priv->clk_desc, GPIOD_IS_OUT);
+ if (ret)
+ goto fail_clk;
+
+ ret = gpio_request_by_name(dev, "dat-gpios", 0,
+ &priv->dat_desc, 0);
+ if (ret)
+ goto fail_dat;
+
+ ret = ht1380_reset_on(priv);
+ if (ret)
+ goto fail;
+
+ return 0;
+
+fail:
+ dm_gpio_free(dev, &priv->dat_desc);
+fail_dat:
+ dm_gpio_free(dev, &priv->clk_desc);
+fail_clk:
+ dm_gpio_free(dev, &priv->rst_desc);
+fail_rst:
+ return ret;
+}
+
+static int ht1380_remove(struct udevice *dev)
+{
+ struct ht1380_priv *priv = dev_get_priv(dev);
+
+ dm_gpio_free(dev, &priv->rst_desc);
+ dm_gpio_free(dev, &priv->clk_desc);
+ dm_gpio_free(dev, &priv->dat_desc);
+
+ return 0;
+}
+
+static const struct rtc_ops ht1380_rtc_ops = {
+ .get = ht1380_rtc_get,
+ .set = ht1380_rtc_set,
+};
+
+static const struct udevice_id ht1380_rtc_ids[] = {
+ { .compatible = "holtek,ht1380" },
+ { }
+};
+
+U_BOOT_DRIVER(rtc_ht1380) = {
+ .name = "rtc-ht1380",
+ .id = UCLASS_RTC,
+ .probe = ht1380_probe,
+ .remove = ht1380_remove,
+ .of_match = ht1380_rtc_ids,
+ .ops = &ht1380_rtc_ops,
+ .priv_auto = sizeof(struct ht1380_priv),
+};
projects / u-boot.git / commitdiff
