rtc: imxdi: Initial support

Add support for Freescale's i.MX DryIce RTC, present on i.MX25.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Acked-by: Stefano Babic <sbabic@denx.de>

drivers/rtc/Makefile

@@ -44,6 +44,7 @@ COBJS-$(CONFIG_RTC_DS164x) += ds164x.o
 COBJS-$(CONFIG_RTC_DS174x) += ds174x.o
 COBJS-$(CONFIG_RTC_DS3231) += ds3231.o
 COBJS-$(CONFIG_RTC_FTRTC010) += ftrtc010.o
+COBJS-$(CONFIG_RTC_IMXDI) += imxdi.o
 COBJS-$(CONFIG_RTC_ISL1208) += isl1208.o
 COBJS-$(CONFIG_RTC_M41T11) += m41t11.o
 COBJS-$(CONFIG_RTC_M41T60) += m41t60.o

drivers/rtc/imxdi.c

@@ -0,0 +1,244 @@
+/*
+ * (C) Copyright 2009-2012 ADVANSEE
+ * Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
+ *
+ * Based on the Linux rtc-imxdi.c driver, which is:
+ * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2010 Orex Computed Radiography
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * Date & Time support for Freescale i.MX DryIce RTC
+ */
+
+#include <common.h>
+#include <command.h>
+#include <linux/compat.h>
+#include <rtc.h>
+
+#if defined(CONFIG_CMD_DATE)
+
+#include <asm/io.h>
+#include <asm/arch/imx-regs.h>
+
+/* DryIce Register Definitions */
+
+struct imxdi_regs {
+	u32 dtcmr;			/* Time Counter MSB Reg */
+	u32 dtclr;			/* Time Counter LSB Reg */
+	u32 dcamr;			/* Clock Alarm MSB Reg */
+	u32 dcalr;			/* Clock Alarm LSB Reg */
+	u32 dcr;			/* Control Reg */
+	u32 dsr;			/* Status Reg */
+	u32 dier;			/* Interrupt Enable Reg */
+};
+
+#define DCAMR_UNSET	0xFFFFFFFF	/* doomsday - 1 sec */
+
+#define DCR_TCE		(1 << 3)	/* Time Counter Enable */
+
+#define DSR_WBF		(1 << 10)	/* Write Busy Flag */
+#define DSR_WNF		(1 << 9)	/* Write Next Flag */
+#define DSR_WCF		(1 << 8)	/* Write Complete Flag */
+#define DSR_WEF		(1 << 7)	/* Write Error Flag */
+#define DSR_CAF		(1 << 4)	/* Clock Alarm Flag */
+#define DSR_NVF		(1 << 1)	/* Non-Valid Flag */
+#define DSR_SVF		(1 << 0)	/* Security Violation Flag */
+
+#define DIER_WNIE	(1 << 9)	/* Write Next Interrupt Enable */
+#define DIER_WCIE	(1 << 8)	/* Write Complete Interrupt Enable */
+#define DIER_WEIE	(1 << 7)	/* Write Error Interrupt Enable */
+#define DIER_CAIE	(1 << 4)	/* Clock Alarm Interrupt Enable */
+
+/* Driver Private Data */
+
+struct imxdi_data {
+	struct imxdi_regs __iomem	*regs;
+	int				init_done;
+};
+
+static struct imxdi_data data;
+
+/*
+ * This function attempts to clear the dryice write-error flag.
+ *
+ * A dryice write error is similar to a bus fault and should not occur in
+ * normal operation.  Clearing the flag requires another write, so the root
+ * cause of the problem may need to be fixed before the flag can be cleared.
+ */
+static void clear_write_error(void)
+{
+	int cnt;
+
+	puts("### Warning: RTC - Register write error!\n");
+
+	/* clear the write error flag */
+	__raw_writel(DSR_WEF, &data.regs->dsr);
+
+	/* wait for it to take effect */
+	for (cnt = 0; cnt < 1000; cnt++) {
+		if ((__raw_readl(&data.regs->dsr) & DSR_WEF) == 0)
+			return;
+		udelay(10);
+	}
+	puts("### Error: RTC - Cannot clear write-error flag!\n");
+}
+
+/*
+ * Write a dryice register and wait until it completes.
+ *
+ * Use interrupt flags to determine when the write has completed.
+ */
+#define DI_WRITE_WAIT(val, reg)						\
+(									\
+	/* do the register write */					\
+	__raw_writel((val), &data.regs->reg),				\
+									\
+	di_write_wait((val), #reg)					\
+)
+static int di_write_wait(u32 val, const char *reg)
+{
+	int cnt;
+	int ret = 0;
+	int rc = 0;
+
+	/* wait for the write to finish */
+	for (cnt = 0; cnt < 100; cnt++) {
+		if ((__raw_readl(&data.regs->dsr) & (DSR_WCF | DSR_WEF)) != 0) {
+			ret = 1;
+			break;
+		}
+		udelay(10);
+	}
+	if (ret == 0)
+		printf("### Warning: RTC - Write-wait timeout "
+				"val = 0x%.8x reg = %s\n", val, reg);
+
+	/* check for write error */
+	if (__raw_readl(&data.regs->dsr) & DSR_WEF) {
+		clear_write_error();
+		rc = -1;
+	}
+
+	return rc;
+}
+
+/*
+ * Initialize dryice hardware
+ */
+static int di_init(void)
+{
+	int rc = 0;
+
+	data.regs = (struct imxdi_regs __iomem *)IMX_DRYICE_BASE;
+
+	/* mask all interrupts */
+	__raw_writel(0, &data.regs->dier);
+
+	/* put dryice into valid state */
+	if (__raw_readl(&data.regs->dsr) & DSR_NVF) {
+		rc = DI_WRITE_WAIT(DSR_NVF | DSR_SVF, dsr);
+		if (rc)
+			goto err;
+	}
+
+	/* initialize alarm */
+	rc = DI_WRITE_WAIT(DCAMR_UNSET, dcamr);
+	if (rc)
+		goto err;
+	rc = DI_WRITE_WAIT(0, dcalr);
+	if (rc)
+		goto err;
+
+	/* clear alarm flag */
+	if (__raw_readl(&data.regs->dsr) & DSR_CAF) {
+		rc = DI_WRITE_WAIT(DSR_CAF, dsr);
+		if (rc)
+			goto err;
+	}
+
+	/* the timer won't count if it has never been written to */
+	if (__raw_readl(&data.regs->dtcmr) == 0) {
+		rc = DI_WRITE_WAIT(0, dtcmr);
+		if (rc)
+			goto err;
+	}
+
+	/* start keeping time */
+	if (!(__raw_readl(&data.regs->dcr) & DCR_TCE)) {
+		rc = DI_WRITE_WAIT(__raw_readl(&data.regs->dcr) | DCR_TCE, dcr);
+		if (rc)
+			goto err;
+	}
+
+	data.init_done = 1;
+	return 0;
+
+err:
+	return rc;
+}
+
+int rtc_get(struct rtc_time *tmp)
+{
+	unsigned long now;
+	int rc = 0;
+
+	if (!data.init_done) {
+		rc = di_init();
+		if (rc)
+			goto err;
+	}
+
+	now = __raw_readl(&data.regs->dtcmr);
+	to_tm(now, tmp);
+
+err:
+	return rc;
+}
+
+int rtc_set(struct rtc_time *tmp)
+{
+	unsigned long now;
+	int rc;
+
+	if (!data.init_done) {
+		rc = di_init();
+		if (rc)
+			goto err;
+	}
+
+	now = mktime(tmp->tm_year, tmp->tm_mon, tmp->tm_mday,
+		     tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
+	/* zero the fractional part first */
+	rc = DI_WRITE_WAIT(0, dtclr);
+	if (rc == 0)
+		rc = DI_WRITE_WAIT(now, dtcmr);
+
+err:
+	return rc;
+}
+
+void rtc_reset(void)
+{
+	di_init();
+}
+
+#endif