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    SubjectRe: [PATCH v2 15/26] RTC: Add JZ4740 RTC driver
    Date
    Dne So 19. června 2010 15:05:18 Lars-Peter Clausen napsal(a):
    > Hi
    >
    > Marek Vasut wrote:
    > > Dne So 19. června 2010 07:08:20 Lars-Peter Clausen napsal(a):
    > >> 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: Wan ZongShun <mcuos.com@gmail.com>
    > >> Cc: Marek Vasut <marek.vasut@gmail.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
    > >> - Fix deadlocks which could occur if the HW was broken
    > >> ---
    > >>
    > >> drivers/rtc/Kconfig | 11 ++
    > >> drivers/rtc/Makefile | 1 +
    > >> drivers/rtc/rtc-jz4740.c | 341
    > >>
    > >> ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 353
    > >> 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..720afb2
    > >> --- /dev/null
    > >> +++ b/drivers/rtc/rtc-jz4740.c
    > >> @@ -0,0 +1,341 @@
    > >> +/*
    > >> + * 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 inline void 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);
    > >
    > > if (!timeout) {
    > >
    > > scream_and_die_in_pain();
    > > dev_err("I died");
    > >
    > > ... or something like that ... what if it times out, in this
    > > implementation, noone will know this failed.
    > >
    > > I haven't looked through the whole source code, but can't this be wrapped
    > > into the reg_write() ?
    > > }
    >
    > Well IF it will ever die, you'll notice cause your rtc clock won't work
    > anymore.

    Then maybe some dev_err() would be good to have there.
    >
    > It could be wrapped into reg_write, but there is a different version of
    > the SoC with the only difference of the RTC unit being that a different
    > mechanism is used determine whether it is ok to write or not. So it
    > makes sense to keep it seperate.

    OK
    >
    > >> +}
    > >> +
    > >> +static inline void jz4740_rtc_reg_write(struct jz4740_rtc *rtc, size_t
    > >> reg, + uint32_t val)
    > >> +{
    > >> + jz4740_rtc_wait_write_ready(rtc);
    > >> + writel(val, rtc->base + reg);
    > >> +}
    > >> +
    > >> +static void jz4740_rtc_ctrl_set_bits(struct jz4740_rtc *rtc, uint32_t
    > >> mask, + uint32_t val)
    > >> +{
    > >> + unsigned long flags;
    > >> + uint32_t ctrl;
    > >> +
    > >> + spin_lock_irqsave(&rtc->lock, flags);
    > >
    > > Can't we use local_irq_save()/local_irq_restore() ?
    >
    > Why would that be preferable? In the non-debug, non-rt case this will
    > expand to local_irq_{save,restore} anyway, but you'll lose the semantics
    > of an lock.

    I believe on SMP systems, local_irq_save will give you finer locking
    granularity.
    >
    > >> +
    > >> + 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;
    > >> +
    > >> + ctrl &= ~mask;
    > >> + ctrl |= val;
    > >> +
    > >> + jz4740_rtc_reg_write(rtc, JZ_REG_RTC_CTRL, ctrl);
    > >> +
    > >> + spin_unlock_irqrestore(&rtc->lock, flags);
    > >> +}
    > >> +
    > >> +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);
    > >> +
    > >> + if ((uint32_t)secs != secs)
    > >> + return -EINVAL;
    > >
    > > Is the typecast here necessary ?
    >
    > Strictly speaking not.

    OK
    >
    > >> +
    > >> + jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, secs);
    > >> +
    > >> + return 0;
    > >> +}
    > >> +
    > >> +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);
    > >> +
    > >
    > > Is the double negation (!!) here necessary ?
    >
    > To quote rtc.h "/* 0 = alarm disabled, 1 = alarm enabled */", so yes.

    Oh my ... well, maybe someone should fix that to take 0 for NO, !0 for YES.
    >
    > >> + 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) +{
    > >> + struct jz4740_rtc *rtc = dev_get_drvdata(dev);
    > >> + unsigned long secs;
    > >> +
    > >> + rtc_tm_to_time(&alrm->time, &secs);
    > >> +
    > >> + if ((uint32_t)secs != secs)
    > >> + return -EINVAL;
    > >
    > > DTTO above
    > >
    > >> +
    > >> + jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC_ALARM, (uint32_t)secs);
    > >
    > > DTTO
    > >
    > >> + jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AE,
    > >> + alrm->enabled ? JZ_RTC_CTRL_AE : 0);
    > >
    > > Possibly the double negation above wasn't necessary
    > >
    > >> +
    > >> + return 0;
    > >> +}
    > >> +
    > >> +static inline int jz4740_irq_enable(struct device *dev, int irq,
    > >> + unsigned int enable)
    > >> +{
    > >> + struct jz4740_rtc *rtc = dev_get_drvdata(dev);
    > >> + jz4740_rtc_ctrl_set_bits(rtc, irq, enable ? irq : 0);
    > >> +
    > >> + return 0;
    > >> +}
    > >> +
    > >> +static int jz4740_rtc_update_irq_enable(struct device *dev, unsigned
    > >> int enable) +{
    > >> + return jz4740_irq_enable(dev, JZ_RTC_CTRL_1HZ_IRQ, enable);
    > >> +}
    > >> +
    > >> +static int jz4740_rtc_alarm_irq_enable(struct device *dev, unsigned int
    > >> enable) +{
    > >> + return jz4740_irq_enable(dev, 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, 0);
    > >> +
    > >> + 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 = kmalloc(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);
    > >
    > > dev_set_drvdata()?
    >
    > No.

    Why not ?
    >
    > >> +
    > >> + 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) {
    > >> + jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SCRATCHPAD, 0x12345678);
    > >> + jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, 0);
    > >> + }
    > >> +
    > >> + return 0;
    > >> +
    > >> +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);
    > >
    > > dev_get_drvdata();
    > >
    > >> +
    > >> + 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);
    > >
    > > DTTO
    > >
    > >> +
    > >> + 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");
    > >
    > > Cheers
    >
    > Thanks for reviewing
    >
    > - Lars
    --
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      Last update: 2010-06-19 16:09    [W:0.070 / U:0.220 seconds]
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