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    Subject[PATCH v3] RTC: Add JZ4740 RTC driver
    Date
    This patch adds support for the RTC unit on JZ4740 SoCs.

    Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
    Cc: Alessandro Zummo <a.zummo@towertech.it>
    Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
    Cc: rtc-linux@googlegroups.com

    --
    Changes since v1
    - Use dev_get_drvdata directly instead of wrapping it in dev_to_rtc
    - Add common implementation for jz4740_rtc_{alarm,update}_irq_enable
    - Check whether rtc structure could be allocated
    - Remove deadlocks which could occur if the HW was broken

    Changes since v2
    - Use kzalloc instead of kmalloc
    - Propagate errors in jz4740_rtc_reg_write up to its callers
    ---
    drivers/rtc/Kconfig | 11 ++
    drivers/rtc/Makefile | 1 +
    drivers/rtc/rtc-jz4740.c | 345 ++++++++++++++++++++++++++++++++++++++++++++++
    3 files changed, 357 insertions(+), 0 deletions(-)
    create mode 100644 drivers/rtc/rtc-jz4740.c

    diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
    index 10ba12c..d0ed7e6 100644
    --- a/drivers/rtc/Kconfig
    +++ b/drivers/rtc/Kconfig
    @@ -905,4 +905,15 @@ config RTC_DRV_MPC5121
    This driver can also be built as a module. If so, the module
    will be called rtc-mpc5121.

    +config RTC_DRV_JZ4740
    + tristate "Ingenic JZ4740 SoC"
    + depends on RTC_CLASS
    + depends on MACH_JZ4740
    + help
    + If you say yes here you get support for the Ingenic JZ4740 SoC RTC
    + controller.
    +
    + This driver can also be buillt as a module. If so, the module
    + will be called rtc-jz4740.
    +
    endif # RTC_CLASS
    diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
    index 5adbba7..fedf9bb 100644
    --- a/drivers/rtc/Makefile
    +++ b/drivers/rtc/Makefile
    @@ -47,6 +47,7 @@ obj-$(CONFIG_RTC_DRV_EP93XX) += rtc-ep93xx.o
    obj-$(CONFIG_RTC_DRV_FM3130) += rtc-fm3130.o
    obj-$(CONFIG_RTC_DRV_GENERIC) += rtc-generic.o
    obj-$(CONFIG_RTC_DRV_ISL1208) += rtc-isl1208.o
    +obj-$(CONFIG_RTC_DRV_JZ4740) += rtc-jz4740.o
    obj-$(CONFIG_RTC_DRV_M41T80) += rtc-m41t80.o
    obj-$(CONFIG_RTC_DRV_M41T94) += rtc-m41t94.o
    obj-$(CONFIG_RTC_DRV_M48T35) += rtc-m48t35.o
    diff --git a/drivers/rtc/rtc-jz4740.c b/drivers/rtc/rtc-jz4740.c
    new file mode 100644
    index 0000000..10b59fc
    --- /dev/null
    +++ b/drivers/rtc/rtc-jz4740.c
    @@ -0,0 +1,345 @@
    +/*
    + * Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
    + * JZ4740 SoC RTC driver
    + *
    + * 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.
    + *
    + * 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.,
    + * 675 Mass Ave, Cambridge, MA 02139, USA.
    + *
    + */
    +
    +#include <linux/kernel.h>
    +#include <linux/module.h>
    +#include <linux/platform_device.h>
    +#include <linux/rtc.h>
    +#include <linux/slab.h>
    +#include <linux/spinlock.h>
    +
    +#define JZ_REG_RTC_CTRL 0x00
    +#define JZ_REG_RTC_SEC 0x04
    +#define JZ_REG_RTC_SEC_ALARM 0x08
    +#define JZ_REG_RTC_REGULATOR 0x0C
    +#define JZ_REG_RTC_HIBERNATE 0x20
    +#define JZ_REG_RTC_SCRATCHPAD 0x34
    +
    +#define JZ_RTC_CTRL_WRDY BIT(7)
    +#define JZ_RTC_CTRL_1HZ BIT(6)
    +#define JZ_RTC_CTRL_1HZ_IRQ BIT(5)
    +#define JZ_RTC_CTRL_AF BIT(4)
    +#define JZ_RTC_CTRL_AF_IRQ BIT(3)
    +#define JZ_RTC_CTRL_AE BIT(2)
    +#define JZ_RTC_CTRL_ENABLE BIT(0)
    +
    +struct jz4740_rtc {
    + struct resource *mem;
    + void __iomem *base;
    +
    + struct rtc_device *rtc;
    +
    + unsigned int irq;
    +
    + spinlock_t lock;
    +};
    +
    +static inline uint32_t jz4740_rtc_reg_read(struct jz4740_rtc *rtc, size_t reg)
    +{
    + return readl(rtc->base + reg);
    +}
    +
    +static int jz4740_rtc_wait_write_ready(struct jz4740_rtc *rtc)
    +{
    + uint32_t ctrl;
    + int timeout = 1000;
    +
    + do {
    + ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
    + } while (!(ctrl & JZ_RTC_CTRL_WRDY) && --timeout);
    +
    + return timeout ? 0 : -EIO;
    +}
    +
    +static inline int jz4740_rtc_reg_write(struct jz4740_rtc *rtc, size_t reg,
    + uint32_t val)
    +{
    + int ret;
    + ret = jz4740_rtc_wait_write_ready(rtc);
    + if (ret == 0)
    + writel(val, rtc->base + reg);
    +
    + return ret;
    +}
    +
    +static int jz4740_rtc_ctrl_set_bits(struct jz4740_rtc *rtc, uint32_t mask,
    + bool set)
    +{
    + int ret;
    + unsigned long flags;
    + uint32_t ctrl;
    +
    + spin_lock_irqsave(&rtc->lock, flags);
    +
    + ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
    +
    + /* Don't clear interrupt flags by accident */
    + ctrl |= JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF;
    +
    + if (set)
    + ctrl |= mask;
    + else
    + ctrl &= ~mask;
    +
    + ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_CTRL, ctrl);
    +
    + spin_unlock_irqrestore(&rtc->lock, flags);
    +
    + return ret;
    +}
    +
    +static int jz4740_rtc_read_time(struct device *dev, struct rtc_time *time)
    +{
    + struct jz4740_rtc *rtc = dev_get_drvdata(dev);
    + uint32_t secs, secs2;
    + int timeout = 5;
    +
    + /* If the seconds register is read while it is updated, it can contain a
    + * bogus value. This can be avoided by making sure that two consecutive
    + * reads have the same value.
    + */
    + secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
    + secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
    +
    + while (secs != secs2 && --timeout) {
    + secs = secs2;
    + secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
    + }
    +
    + if (timeout == 0)
    + return -EIO;
    +
    + rtc_time_to_tm(secs, time);
    +
    + return rtc_valid_tm(time);
    +}
    +
    +static int jz4740_rtc_set_mmss(struct device *dev, unsigned long secs)
    +{
    + struct jz4740_rtc *rtc = dev_get_drvdata(dev);
    +
    + return jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, secs);
    +}
    +
    +static int jz4740_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
    +{
    + struct jz4740_rtc *rtc = dev_get_drvdata(dev);
    + uint32_t secs;
    + uint32_t ctrl;
    +
    + secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC_ALARM);
    +
    + ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
    +
    + alrm->enabled = !!(ctrl & JZ_RTC_CTRL_AE);
    + alrm->pending = !!(ctrl & JZ_RTC_CTRL_AF);
    +
    + rtc_time_to_tm(secs, &alrm->time);
    +
    + return rtc_valid_tm(&alrm->time);
    +}
    +
    +static int jz4740_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
    +{
    + int ret;
    + struct jz4740_rtc *rtc = dev_get_drvdata(dev);
    + unsigned long secs;
    +
    + rtc_tm_to_time(&alrm->time, &secs);
    +
    + ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC_ALARM, secs);
    + if (!ret)
    + ret = jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AE, alrm->enabled);
    +
    + return ret;
    +}
    +
    +static int jz4740_rtc_update_irq_enable(struct device *dev, unsigned int enable)
    +{
    + struct jz4740_rtc *rtc = dev_get_drvdata(dev);
    + return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_1HZ_IRQ, enable);
    +}
    +
    +static int jz4740_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
    +{
    + struct jz4740_rtc *rtc = dev_get_drvdata(dev);
    + return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AF_IRQ, enable);
    +}
    +
    +static struct rtc_class_ops jz4740_rtc_ops = {
    + .read_time = jz4740_rtc_read_time,
    + .set_mmss = jz4740_rtc_set_mmss,
    + .read_alarm = jz4740_rtc_read_alarm,
    + .set_alarm = jz4740_rtc_set_alarm,
    + .update_irq_enable = jz4740_rtc_update_irq_enable,
    + .alarm_irq_enable = jz4740_rtc_alarm_irq_enable,
    +};
    +
    +static irqreturn_t jz4740_rtc_irq(int irq, void *data)
    +{
    + struct jz4740_rtc *rtc = data;
    + uint32_t ctrl;
    + unsigned long events = 0;
    +
    + ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
    +
    + if (ctrl & JZ_RTC_CTRL_1HZ)
    + events |= (RTC_UF | RTC_IRQF);
    +
    + if (ctrl & JZ_RTC_CTRL_AF)
    + events |= (RTC_AF | RTC_IRQF);
    +
    + rtc_update_irq(rtc->rtc, 1, events);
    +
    + jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF, false);
    +
    + return IRQ_HANDLED;
    +}
    +
    +void jz4740_rtc_poweroff(struct device *dev)
    +{
    + struct jz4740_rtc *rtc = dev_get_drvdata(dev);
    + jz4740_rtc_reg_write(rtc, JZ_REG_RTC_HIBERNATE, 1);
    +}
    +EXPORT_SYMBOL_GPL(jz4740_rtc_poweroff);
    +
    +static int __devinit jz4740_rtc_probe(struct platform_device *pdev)
    +{
    + int ret;
    + struct jz4740_rtc *rtc;
    + uint32_t scratchpad;
    +
    + rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
    + if (!rtc)
    + return -ENOMEM;
    +
    + rtc->irq = platform_get_irq(pdev, 0);
    + if (rtc->irq < 0) {
    + ret = -ENOENT;
    + dev_err(&pdev->dev, "Failed to get platform irq\n");
    + goto err_free;
    + }
    +
    + rtc->mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    + if (!rtc->mem) {
    + ret = -ENOENT;
    + dev_err(&pdev->dev, "Failed to get platform mmio memory\n");
    + goto err_free;
    + }
    +
    + rtc->mem = request_mem_region(rtc->mem->start, resource_size(rtc->mem),
    + pdev->name);
    + if (!rtc->mem) {
    + ret = -EBUSY;
    + dev_err(&pdev->dev, "Failed to request mmio memory region\n");
    + goto err_free;
    + }
    +
    + rtc->base = ioremap_nocache(rtc->mem->start, resource_size(rtc->mem));
    + if (!rtc->base) {
    + ret = -EBUSY;
    + dev_err(&pdev->dev, "Failed to ioremap mmio memory\n");
    + goto err_release_mem_region;
    + }
    +
    + spin_lock_init(&rtc->lock);
    +
    + platform_set_drvdata(pdev, rtc);
    +
    + rtc->rtc = rtc_device_register(pdev->name, &pdev->dev, &jz4740_rtc_ops,
    + THIS_MODULE);
    + if (IS_ERR(rtc->rtc)) {
    + ret = PTR_ERR(rtc->rtc);
    + dev_err(&pdev->dev, "Failed to register rtc device: %d\n", ret);
    + goto err_iounmap;
    + }
    +
    + ret = request_irq(rtc->irq, jz4740_rtc_irq, 0,
    + pdev->name, rtc);
    + if (ret) {
    + dev_err(&pdev->dev, "Failed to request rtc irq: %d\n", ret);
    + goto err_unregister_rtc;
    + }
    +
    + scratchpad = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SCRATCHPAD);
    + if (scratchpad != 0x12345678) {
    + ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SCRATCHPAD, 0x12345678);
    + ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, 0);
    + if (ret) {
    + dev_err(&pdev->dev, "Could not write write to RTC registers\n");
    + goto err_free_irq;
    + }
    + }
    +
    + return 0;
    +
    +err_free_irq:
    + free_irq(rtc->irq, rtc);
    +err_unregister_rtc:
    + rtc_device_unregister(rtc->rtc);
    +err_iounmap:
    + platform_set_drvdata(pdev, NULL);
    + iounmap(rtc->base);
    +err_release_mem_region:
    + release_mem_region(rtc->mem->start, resource_size(rtc->mem));
    +err_free:
    + kfree(rtc);
    +
    + return ret;
    +}
    +
    +static int __devexit jz4740_rtc_remove(struct platform_device *pdev)
    +{
    + struct jz4740_rtc *rtc = platform_get_drvdata(pdev);
    +
    + free_irq(rtc->irq, rtc);
    +
    + rtc_device_unregister(rtc->rtc);
    +
    + iounmap(rtc->base);
    + release_mem_region(rtc->mem->start, resource_size(rtc->mem));
    +
    + kfree(rtc);
    +
    + platform_set_drvdata(pdev, NULL);
    +
    + return 0;
    +}
    +
    +struct platform_driver jz4740_rtc_driver = {
    + .probe = jz4740_rtc_probe,
    + .remove = __devexit_p(jz4740_rtc_remove),
    + .driver = {
    + .name = "jz4740-rtc",
    + .owner = THIS_MODULE,
    + },
    +};
    +
    +static int __init jz4740_rtc_init(void)
    +{
    + return platform_driver_register(&jz4740_rtc_driver);
    +}
    +module_init(jz4740_rtc_init);
    +
    +static void __exit jz4740_rtc_exit(void)
    +{
    + platform_driver_unregister(&jz4740_rtc_driver);
    +}
    +module_exit(jz4740_rtc_exit);
    +
    +MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
    +MODULE_LICENSE("GPL");
    +MODULE_DESCRIPTION("RTC driver for the JZ4740 SoC\n");
    +MODULE_ALIAS("platform:jz4740-rtc");
    --
    1.5.6.5


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