[PATCH] RTC subsystem: SA1100/PXA2XX driver

Add an RTC subsystem driver for the ARM SA1100/PXA2XX processor RTC.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 398 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index b399259784e2..166232a3f56b 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -127,6 +127,15 @@ config RTC_DRV_EP93XX
           This driver can also be built as a module. If so, the module
           will be called rtc-ep93xx.
 
+config RTC_DRV_SA1100
+        tristate "SA11x0/PXA2xx"
+        depends on RTC_CLASS && (ARCH_SA1100 || ARCH_PXA)
+        help
+          If you say Y here you will get access to the real time clock
+          built into your SA11x0 or PXA2xx CPU.
+
+          To compile this driver as a module, choose M here: the
+          module will be called rtc-sa1100.
 
 config RTC_DRV_TEST
         tristate "Test driver/device"
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 38b4d87939e1..56820d18161e 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -17,3 +17,4 @@ obj-$(CONFIG_RTC_DRV_DS1672)	+= rtc-ds1672.o
 obj-$(CONFIG_RTC_DRV_PCF8563)   += rtc-pcf8563.o
 obj-$(CONFIG_RTC_DRV_RS5C372)   += rtc-rs5c372.o
 obj-$(CONFIG_RTC_DRV_EP93XX)    += rtc-ep93xx.o
+obj-$(CONFIG_RTC_DRV_SA1100)    += rtc-sa1100.o
diff --git a/drivers/rtc/rtc-sa1100.c b/drivers/rtc/rtc-sa1100.c
new file mode 100644
index 000000000000..83b2bb480a16
--- /dev/null
+++ b/drivers/rtc/rtc-sa1100.c
@@ -0,0 +1,388 @@
+/*
+ * Real Time Clock interface for StrongARM SA1x00 and XScale PXA2xx
+ *
+ * Copyright (c) 2000 Nils Faerber
+ *
+ * Based on rtc.c by Paul Gortmaker
+ *
+ * Original Driver by Nils Faerber <nils@kernelconcepts.de>
+ *
+ * Modifications from:
+ *   CIH <cih@coventive.com>
+ *   Nicolas Pitre <nico@cam.org>
+ *   Andrew Christian <andrew.christian@hp.com>
+ *
+ * Converted to the RTC subsystem and Driver Model
+ *   by Richard Purdie <rpurdie@rpsys.net>
+ *
+ * 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.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <linux/string.h>
+#include <linux/pm.h>
+
+#include <asm/bitops.h>
+#include <asm/hardware.h>
+#include <asm/irq.h>
+#include <asm/rtc.h>
+
+#ifdef CONFIG_ARCH_PXA
+#include <asm/arch/pxa-regs.h>
+#endif
+
+#define TIMER_FREQ              CLOCK_TICK_RATE
+#define RTC_DEF_DIVIDER         32768 - 1
+#define RTC_DEF_TRIM            0
+
+static unsigned long rtc_freq = 1024;
+static struct rtc_time rtc_alarm;
+static spinlock_t sa1100_rtc_lock = SPIN_LOCK_UNLOCKED;
+
+static int rtc_update_alarm(struct rtc_time *alrm)
+{
+        struct rtc_time alarm_tm, now_tm;
+        unsigned long now, time;
+        int ret;
+
+        do {
+                now = RCNR;
+                rtc_time_to_tm(now, &now_tm);
+                rtc_next_alarm_time(&alarm_tm, &now_tm, alrm);
+                ret = rtc_tm_to_time(&alarm_tm, &time);
+                if (ret != 0)
+                        break;
+
+                RTSR = RTSR & (RTSR_HZE|RTSR_ALE|RTSR_AL);
+                RTAR = time;
+        } while (now != RCNR);
+
+        return ret;
+}
+
+static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id,
+                struct pt_regs *regs)
+{
+        struct platform_device *pdev = to_platform_device(dev_id);
+        struct rtc_device *rtc = platform_get_drvdata(pdev);
+        unsigned int rtsr;
+        unsigned long events = 0;
+
+        spin_lock(&sa1100_rtc_lock);
+
+        rtsr = RTSR;
+        /* clear interrupt sources */
+        RTSR = 0;
+        RTSR = (RTSR_AL | RTSR_HZ) & (rtsr >> 2);
+
+        /* clear alarm interrupt if it has occurred */
+        if (rtsr & RTSR_AL)
+                rtsr &= ~RTSR_ALE;
+        RTSR = rtsr & (RTSR_ALE | RTSR_HZE);
+
+        /* update irq data & counter */
+        if (rtsr & RTSR_AL)
+                events |= RTC_AF | RTC_IRQF;
+        if (rtsr & RTSR_HZ)
+                events |= RTC_UF | RTC_IRQF;
+
+        rtc_update_irq(&rtc->class_dev, 1, events);
+
+        if (rtsr & RTSR_AL && rtc_periodic_alarm(&rtc_alarm))
+                rtc_update_alarm(&rtc_alarm);
+
+        spin_unlock(&sa1100_rtc_lock);
+
+        return IRQ_HANDLED;
+}
+
+static int rtc_timer1_count;
+
+static irqreturn_t timer1_interrupt(int irq, void *dev_id,
+                struct pt_regs *regs)
+{
+        struct platform_device *pdev = to_platform_device(dev_id);
+        struct rtc_device *rtc = platform_get_drvdata(pdev);
+
+        /*
+         * If we match for the first time, rtc_timer1_count will be 1.
+         * Otherwise, we wrapped around (very unlikely but
+         * still possible) so compute the amount of missed periods.
+         * The match reg is updated only when the data is actually retrieved
+         * to avoid unnecessary interrupts.
+         */
+        OSSR = OSSR_M1; /* clear match on timer1 */
+
+        rtc_update_irq(&rtc->class_dev, rtc_timer1_count, RTC_PF | RTC_IRQF);
+
+        if (rtc_timer1_count == 1)
+                rtc_timer1_count = (rtc_freq * ((1<<30)/(TIMER_FREQ>>2)));
+
+        return IRQ_HANDLED;
+}
+
+static int sa1100_rtc_read_callback(struct device *dev, int data)
+{
+        if (data & RTC_PF) {
+                /* interpolate missed periods and set match for the next */
+                unsigned long period = TIMER_FREQ/rtc_freq;
+                unsigned long oscr = OSCR;
+                unsigned long osmr1 = OSMR1;
+                unsigned long missed = (oscr - osmr1)/period;
+                data += missed << 8;
+                OSSR = OSSR_M1; /* clear match on timer 1 */
+                OSMR1 = osmr1 + (missed + 1)*period;
+                /* Ensure we didn't miss another match in the mean time.
+                 * Here we compare (match - OSCR) 8 instead of 0 --
+                 * see comment in pxa_timer_interrupt() for explanation.
+                 */
+                while( (signed long)((osmr1 = OSMR1) - OSCR) <= 8 ) {
+                        data += 0x100;
+                        OSSR = OSSR_M1; /* clear match on timer 1 */
+                        OSMR1 = osmr1 + period;
+                }
+        }
+        return data;
+}
+
+static int sa1100_rtc_open(struct device *dev)
+{
+        int ret;
+
+        ret = request_irq(IRQ_RTC1Hz, sa1100_rtc_interrupt, SA_INTERRUPT,
+                                "rtc 1Hz", dev);
+        if (ret) {
+                printk(KERN_ERR "rtc: IRQ%d already in use.\n", IRQ_RTC1Hz);
+                goto fail_ui;
+        }
+        ret = request_irq(IRQ_RTCAlrm, sa1100_rtc_interrupt, SA_INTERRUPT,
+                                "rtc Alrm", dev);
+        if (ret) {
+                printk(KERN_ERR "rtc: IRQ%d already in use.\n", IRQ_RTCAlrm);
+                goto fail_ai;
+        }
+        ret = request_irq(IRQ_OST1, timer1_interrupt, SA_INTERRUPT,
+                                "rtc timer", dev);
+        if (ret) {
+                printk(KERN_ERR "rtc: IRQ%d already in use.\n", IRQ_OST1);
+                goto fail_pi;
+        }
+        return 0;
+
+ fail_pi:
+        free_irq(IRQ_RTCAlrm, NULL);
+ fail_ai:
+        free_irq(IRQ_RTC1Hz, NULL);
+ fail_ui:
+        return ret;
+}
+
+static void sa1100_rtc_release(struct device *dev)
+{
+        spin_lock_irq(&sa1100_rtc_lock);
+        RTSR = 0;
+        OIER &= ~OIER_E1;
+        OSSR = OSSR_M1;
+        spin_unlock_irq(&sa1100_rtc_lock);
+
+        free_irq(IRQ_OST1, dev);
+        free_irq(IRQ_RTCAlrm, dev);
+        free_irq(IRQ_RTC1Hz, dev);
+}
+
+
+static int sa1100_rtc_ioctl(struct device *dev, unsigned int cmd,
+                unsigned long arg)
+{
+        switch(cmd) {
+        case RTC_AIE_OFF:
+                spin_lock_irq(&sa1100_rtc_lock);
+                RTSR &= ~RTSR_ALE;
+                spin_unlock_irq(&sa1100_rtc_lock);
+                return 0;
+        case RTC_AIE_ON:
+                spin_lock_irq(&sa1100_rtc_lock);
+                RTSR |= RTSR_ALE;
+                spin_unlock_irq(&sa1100_rtc_lock);
+                return 0;
+        case RTC_UIE_OFF:
+                spin_lock_irq(&sa1100_rtc_lock);
+                RTSR &= ~RTSR_HZE;
+                spin_unlock_irq(&sa1100_rtc_lock);
+                return 0;
+        case RTC_UIE_ON:
+                spin_lock_irq(&sa1100_rtc_lock);
+                RTSR |= RTSR_HZE;
+                spin_unlock_irq(&sa1100_rtc_lock);
+                return 0;
+        case RTC_PIE_OFF:
+                spin_lock_irq(&sa1100_rtc_lock);
+                OIER &= ~OIER_E1;
+                spin_unlock_irq(&sa1100_rtc_lock);
+                return 0;
+        case RTC_PIE_ON:
+                if ((rtc_freq > 64) && !capable(CAP_SYS_RESOURCE))
+                        return -EACCES;
+                spin_lock_irq(&sa1100_rtc_lock);
+                OSMR1 = TIMER_FREQ/rtc_freq + OSCR;
+                OIER |= OIER_E1;
+                rtc_timer1_count = 1;
+                spin_unlock_irq(&sa1100_rtc_lock);
+                return 0;
+        case RTC_IRQP_READ:
+                return put_user(rtc_freq, (unsigned long *)arg);
+        case RTC_IRQP_SET:
+                if (arg < 1 || arg > TIMER_FREQ)
+                        return -EINVAL;
+                if ((arg > 64) && (!capable(CAP_SYS_RESOURCE)))
+                        return -EACCES;
+                rtc_freq = arg;
+                return 0;
+        }
+        return -EINVAL;
+}
+
+static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        rtc_time_to_tm(RCNR, tm);
+        return 0;
+}
+
+static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        unsigned long time;
+        int ret;
+
+        ret = rtc_tm_to_time(tm, &time);
+        if (ret == 0)
+                RCNR = time;
+        return ret;
+}
+
+static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        memcpy(&alrm->time, &rtc_alarm, sizeof(struct rtc_time));
+        alrm->pending = RTSR & RTSR_AL ? 1 : 0;
+        return 0;
+}
+
+static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        int ret;
+
+        spin_lock_irq(&sa1100_rtc_lock);
+        ret = rtc_update_alarm(&alrm->time);
+        if (ret == 0) {
+                memcpy(&rtc_alarm, &alrm->time, sizeof(struct rtc_time));
+
+                if (alrm->enabled)
+                        enable_irq_wake(IRQ_RTCAlrm);
+                else
+                        disable_irq_wake(IRQ_RTCAlrm);
+        }
+        spin_unlock_irq(&sa1100_rtc_lock);
+
+        return ret;
+}
+
+static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+        seq_printf(seq, "trim/divider\t: 0x%08x\n", RTTR);
+        seq_printf(seq, "alarm_IRQ\t: %s\n",
+                        (RTSR & RTSR_ALE) ? "yes" : "no" );
+        seq_printf(seq, "update_IRQ\t: %s\n",
+                        (RTSR & RTSR_HZE) ? "yes" : "no");
+        seq_printf(seq, "periodic_IRQ\t: %s\n",
+                        (OIER & OIER_E1) ? "yes" : "no");
+        seq_printf(seq, "periodic_freq\t: %ld\n", rtc_freq);
+
+        return 0;
+}
+
+static struct rtc_class_ops sa1100_rtc_ops = {
+        .open = sa1100_rtc_open,
+        .read_callback = sa1100_rtc_read_callback,
+        .release = sa1100_rtc_release,
+        .ioctl = sa1100_rtc_ioctl,
+        .read_time = sa1100_rtc_read_time,
+        .set_time = sa1100_rtc_set_time,
+        .read_alarm = sa1100_rtc_read_alarm,
+        .set_alarm = sa1100_rtc_set_alarm,
+        .proc = sa1100_rtc_proc,
+};
+
+static int sa1100_rtc_probe(struct platform_device *pdev)
+{
+        struct rtc_device *rtc;
+
+        /*
+         * According to the manual we should be able to let RTTR be zero
+         * and then a default diviser for a 32.768KHz clock is used.
+         * Apparently this doesn't work, at least for my SA1110 rev 5.
+         * If the clock divider is uninitialized then reset it to the
+         * default value to get the 1Hz clock.
+         */
+        if (RTTR == 0) {
+                RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
+                printk(KERN_WARNING "rtc: warning: initializing default clock divider/trim value\n");
+                /* The current RTC value probably doesn't make sense either */
+                RCNR = 0;
+        }
+
+        rtc = rtc_device_register(pdev->name, &pdev->dev, &sa1100_rtc_ops,
+                                THIS_MODULE);
+
+        if (IS_ERR(rtc)) {
+                dev_err(&pdev->dev, "Unable to register the RTC device\n");
+                return PTR_ERR(rtc);
+        }
+
+        platform_set_drvdata(pdev, rtc);
+
+        dev_info(&pdev->dev, "SA11xx/PXA2xx RTC Registered\n");
+
+        return 0;
+}
+
+static int sa1100_rtc_remove(struct platform_device *pdev)
+{
+        struct rtc_device *rtc = platform_get_drvdata(pdev);
+
+        if (rtc)
+                rtc_device_unregister(rtc);
+
+        return 0;
+}
+
+static struct platform_driver sa1100_rtc_driver = {
+        .probe          = sa1100_rtc_probe,
+        .remove         = sa1100_rtc_remove,
+        .driver         = {
+                .name           = "sa1100-rtc",
+        },
+};
+
+static int __init sa1100_rtc_init(void)
+{
+        return platform_driver_register(&sa1100_rtc_driver);
+}
+
+static void __exit sa1100_rtc_exit(void)
+{
+        platform_driver_unregister(&sa1100_rtc_driver);
+}
+
+module_init(sa1100_rtc_init);
+module_exit(sa1100_rtc_exit);
+
+MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
+MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
+MODULE_LICENSE("GPL");