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Date: Sat, 19 Jun 2010 19:42:33 +0200
From: Lars-Peter Clausen <lars@...afoo.de>
To: Marek Vasut <marek.vasut@...il.com>
CC: Ralf Baechle <ralf@...ux-mips.org>, linux-mips@...ux-mips.org,
linux-kernel@...r.kernel.org,
Alessandro Zummo <a.zummo@...ertech.it>,
Paul Gortmaker <p_gortmaker@...oo.com>,
Wan ZongShun <mcuos.com@...il.com>, rtc-linux@...glegroups.com
Subject: Re: [PATCH v2 15/26] RTC: Add JZ4740 RTC driver
Marek Vasut wrote:
> 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@...afoo.de>
>>>> Cc: Alessandro Zummo <a.zummo@...ertech.it>
>>>> Cc: Paul Gortmaker <p_gortmaker@...oo.com>
>>>> Cc: Wan ZongShun <mcuos.com@...il.com>
>>>> Cc: Marek Vasut <marek.vasut@...il.com>
>>>> Cc: rtc-linux@...glegroups.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@...afoo.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.
>
That would spam the kernel log. The best solution would be to propagate
a -EIO up to rtc_ops callers. But I'm not sure if the overhead is worth
it given that the case will virtually never happen. But I'll think about it.
>> 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.
>
Hm, not sure about that. But this is on a non SMP system anyway.
>>>> +
>>>> + 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.
>
Well, it's part of the userspace api.
>>>> + 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 ?
>
platform_set_drvdata(pdev, data) expands to dev_set_drvdata(&(pdev)->dev, data)
- Lars
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