Driver for the Atmel on-chip RTC on AT32AP700x devices

Tested on the AT32AP7000/ATSTK1000.  Driver does only suport time, wake up
and a very simple alarm, because of hardware limitations.

Hardware documentation can be found in the AT32AP7000 data sheet, which can
be downloaded from

http://www.atmel.com/dyn/products/datasheets.asp?family_id=682

From: David Brownell <david-b@pacbell.net>

 - Strike some alarm setup code that's no longer needed.
   (This patch seems to have gotten lost somewhere...)

 - Make the driver name (and its module alias) match what
   the platform setup code uses, so the driver can bind
   and hotplug.

[akpm@linux-foundation.org: fix several checkpatch.pl warnings]
Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 317 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-at32ap700x.c b/drivers/rtc/rtc-at32ap700x.c
new file mode 100644
index 000000000000..2999214ca534
--- /dev/null
+++ b/drivers/rtc/rtc-at32ap700x.c
@@ -0,0 +1,317 @@
+/*
+ * An RTC driver for the AVR32 AT32AP700x processor series.
+ *
+ * Copyright (C) 2007 Atmel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/io.h>
+
+/*
+ * This is a bare-bones RTC. It runs during most system sleep states, but has
+ * no battery backup and gets reset during system restart.  It must be
+ * initialized from an external clock (network, I2C, etc) before it can be of
+ * much use.
+ *
+ * The alarm functionality is limited by the hardware, not supporting
+ * periodic interrupts.
+ */
+
+#define RTC_CTRL                0x00
+#define RTC_CTRL_EN                0
+#define RTC_CTRL_PCLR              1
+#define RTC_CTRL_TOPEN             2
+#define RTC_CTRL_PSEL              8
+
+#define RTC_VAL                 0x04
+
+#define RTC_TOP                 0x08
+
+#define RTC_IER                 0x10
+#define RTC_IER_TOPI               0
+
+#define RTC_IDR                 0x14
+#define RTC_IDR_TOPI               0
+
+#define RTC_IMR                 0x18
+#define RTC_IMR_TOPI               0
+
+#define RTC_ISR                 0x1c
+#define RTC_ISR_TOPI               0
+
+#define RTC_ICR                 0x20
+#define RTC_ICR_TOPI               0
+
+#define RTC_BIT(name)           (1 << RTC_##name)
+#define RTC_BF(name, value)     ((value) << RTC_##name)
+
+#define rtc_readl(dev, reg)                             \
+        __raw_readl((dev)->regs + RTC_##reg)
+#define rtc_writel(dev, reg, value)                     \
+        __raw_writel((value), (dev)->regs + RTC_##reg)
+
+struct rtc_at32ap700x {
+        struct rtc_device       *rtc;
+        void __iomem            *regs;
+        unsigned long           alarm_time;
+        unsigned long           irq;
+        /* Protect against concurrent register access. */
+        spinlock_t              lock;
+};
+
+static int at32_rtc_readtime(struct device *dev, struct rtc_time *tm)
+{
+        struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
+        unsigned long now;
+
+        now = rtc_readl(rtc, VAL);
+        rtc_time_to_tm(now, tm);
+
+        return 0;
+}
+
+static int at32_rtc_settime(struct device *dev, struct rtc_time *tm)
+{
+        struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
+        unsigned long now;
+        int ret;
+
+        ret = rtc_tm_to_time(tm, &now);
+        if (ret == 0)
+                rtc_writel(rtc, VAL, now);
+
+        return ret;
+}
+
+static int at32_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
+
+        rtc_time_to_tm(rtc->alarm_time, &alrm->time);
+        alrm->pending = rtc_readl(rtc, IMR) & RTC_BIT(IMR_TOPI) ? 1 : 0;
+
+        return 0;
+}
+
+static int at32_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
+        unsigned long rtc_unix_time;
+        unsigned long alarm_unix_time;
+        int ret;
+
+        rtc_unix_time = rtc_readl(rtc, VAL);
+
+        ret = rtc_tm_to_time(&alrm->time, &alarm_unix_time);
+        if (ret)
+                return ret;
+
+        if (alarm_unix_time < rtc_unix_time)
+                return -EINVAL;
+
+        spin_lock_irq(&rtc->lock);
+        rtc->alarm_time = alarm_unix_time;
+        rtc_writel(rtc, TOP, rtc->alarm_time);
+        if (alrm->pending)
+                rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
+                                | RTC_BIT(CTRL_TOPEN));
+        else
+                rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
+                                & ~RTC_BIT(CTRL_TOPEN));
+        spin_unlock_irq(&rtc->lock);
+
+        return ret;
+}
+
+static int at32_rtc_ioctl(struct device *dev, unsigned int cmd,
+                        unsigned long arg)
+{
+        struct rtc_at32ap700x *rtc = dev_get_drvdata(dev);
+        int ret = 0;
+
+        spin_lock_irq(&rtc->lock);
+
+        switch (cmd) {
+        case RTC_AIE_ON:
+                if (rtc_readl(rtc, VAL) > rtc->alarm_time) {
+                        ret = -EINVAL;
+                        break;
+                }
+                rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
+                                | RTC_BIT(CTRL_TOPEN));
+                rtc_writel(rtc, ICR, RTC_BIT(ICR_TOPI));
+                rtc_writel(rtc, IER, RTC_BIT(IER_TOPI));
+                break;
+        case RTC_AIE_OFF:
+                rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
+                                & ~RTC_BIT(CTRL_TOPEN));
+                rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
+                rtc_writel(rtc, ICR, RTC_BIT(ICR_TOPI));
+                break;
+        default:
+                ret = -ENOIOCTLCMD;
+                break;
+        }
+
+        spin_unlock_irq(&rtc->lock);
+
+        return ret;
+}
+
+static irqreturn_t at32_rtc_interrupt(int irq, void *dev_id)
+{
+        struct rtc_at32ap700x *rtc = (struct rtc_at32ap700x *)dev_id;
+        unsigned long isr = rtc_readl(rtc, ISR);
+        unsigned long events = 0;
+        int ret = IRQ_NONE;
+
+        spin_lock(&rtc->lock);
+
+        if (isr & RTC_BIT(ISR_TOPI)) {
+                rtc_writel(rtc, ICR, RTC_BIT(ICR_TOPI));
+                rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
+                rtc_writel(rtc, CTRL, rtc_readl(rtc, CTRL)
+                                & ~RTC_BIT(CTRL_TOPEN));
+                rtc_writel(rtc, VAL, rtc->alarm_time);
+                events = RTC_AF | RTC_IRQF;
+                rtc_update_irq(rtc->rtc, 1, events);
+                ret = IRQ_HANDLED;
+        }
+
+        spin_unlock(&rtc->lock);
+
+        return ret;
+}
+
+static struct rtc_class_ops at32_rtc_ops = {
+        .ioctl          = at32_rtc_ioctl,
+        .read_time      = at32_rtc_readtime,
+        .set_time       = at32_rtc_settime,
+        .read_alarm     = at32_rtc_readalarm,
+        .set_alarm      = at32_rtc_setalarm,
+};
+
+static int __init at32_rtc_probe(struct platform_device *pdev)
+{
+        struct resource *regs;
+        struct rtc_at32ap700x *rtc;
+        int irq = -1;
+        int ret;
+
+        rtc = kzalloc(sizeof(struct rtc_at32ap700x), GFP_KERNEL);
+        if (!rtc) {
+                dev_dbg(&pdev->dev, "out of memory\n");
+                return -ENOMEM;
+        }
+
+        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!regs) {
+                dev_dbg(&pdev->dev, "no mmio resource defined\n");
+                ret = -ENXIO;
+                goto out;
+        }
+
+        irq = platform_get_irq(pdev, 0);
+        if (irq < 0) {
+                dev_dbg(&pdev->dev, "could not get irq\n");
+                ret = -ENXIO;
+                goto out;
+        }
+
+        ret = request_irq(irq, at32_rtc_interrupt, IRQF_SHARED, "rtc", rtc);
+        if (ret) {
+                dev_dbg(&pdev->dev, "could not request irq %d\n", irq);
+                goto out;
+        }
+
+        rtc->irq = irq;
+        rtc->regs = ioremap(regs->start, regs->end - regs->start + 1);
+        if (!rtc->regs) {
+                ret = -ENOMEM;
+                dev_dbg(&pdev->dev, "could not map I/O memory\n");
+                goto out_free_irq;
+        }
+        spin_lock_init(&rtc->lock);
+
+        /*
+         * Maybe init RTC: count from zero at 1 Hz, disable wrap irq.
+         *
+         * Do not reset VAL register, as it can hold an old time
+         * from last JTAG reset.
+         */
+        if (!(rtc_readl(rtc, CTRL) & RTC_BIT(CTRL_EN))) {
+                rtc_writel(rtc, CTRL, RTC_BIT(CTRL_PCLR));
+                rtc_writel(rtc, IDR, RTC_BIT(IDR_TOPI));
+                rtc_writel(rtc, CTRL, RTC_BF(CTRL_PSEL, 0xe)
+                                | RTC_BIT(CTRL_EN));
+        }
+
+        rtc->rtc = rtc_device_register(pdev->name, &pdev->dev,
+                                &at32_rtc_ops, THIS_MODULE);
+        if (IS_ERR(rtc->rtc)) {
+                dev_dbg(&pdev->dev, "could not register rtc device\n");
+                ret = PTR_ERR(rtc->rtc);
+                goto out_iounmap;
+        }
+
+        platform_set_drvdata(pdev, rtc);
+
+        dev_info(&pdev->dev, "Atmel RTC for AT32AP700x at %08lx irq %ld\n",
+                        (unsigned long)rtc->regs, rtc->irq);
+
+        return 0;
+
+out_iounmap:
+        iounmap(rtc->regs);
+out_free_irq:
+        free_irq(irq, rtc);
+out:
+        kfree(rtc);
+        return ret;
+}
+
+static int __exit at32_rtc_remove(struct platform_device *pdev)
+{
+        struct rtc_at32ap700x *rtc = platform_get_drvdata(pdev);
+
+        free_irq(rtc->irq, rtc);
+        iounmap(rtc->regs);
+        rtc_device_unregister(rtc->rtc);
+        kfree(rtc);
+        platform_set_drvdata(pdev, NULL);
+
+        return 0;
+}
+
+MODULE_ALIAS("at32ap700x_rtc");
+
+static struct platform_driver at32_rtc_driver = {
+        .remove         = __exit_p(at32_rtc_remove),
+        .driver         = {
+                .name   = "at32ap700x_rtc",
+                .owner  = THIS_MODULE,
+        },
+};
+
+static int __init at32_rtc_init(void)
+{
+        return platform_driver_probe(&at32_rtc_driver, at32_rtc_probe);
+}
+module_init(at32_rtc_init);
+
+static void __exit at32_rtc_exit(void)
+{
+        platform_driver_unregister(&at32_rtc_driver);
+}
+module_exit(at32_rtc_exit);
+
+MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
+MODULE_DESCRIPTION("Real time clock for AVR32 AT32AP700x");
+MODULE_LICENSE("GPL");