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Message-ID: <AANLkTikc_aHiRhPds-_CEMma_J9thmbai2nkcYFZPp9h@mail.gmail.com>
Date: Sun, 13 Jun 2010 21:41:33 +0800
From: Wan ZongShun <mcuos.com@...il.com>
To: rtc-linux@...glegroups.com,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Alessandro Zummo <a.zummo@...ertech.it>,
"Linux/m68k" <linux-m68k@...ts.linux-m68k.org>,
Linux Kernel Development <linux-kernel@...r.kernel.org>
Subject: Re: [rtc-linux] [PATCH] rtc: rp5c01 - Add NVRAM support
Hi Geert ,
Minior comment below:
2010/6/13 Geert Uytterhoeven <geert@...ux-m68k.org>:
> The Ricoh RP5C01 RTC contains 26 x 4 bits of NVRAM.
> Provide access to it via a sysfs "nvram" attribute file.
>
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> --
> Question: Is a spinlock in priv the right kind of locking?
> Should I use e.g. rtc-device.ops_lock instead?
Firstly, this 'Question' text should not put here, please put all
texts in front of '---'.
Secondly, You can not use rtc-device.ops_lock here, if so, it would
arouse dead lock,
before the ' rp5c01_read_time()' was called by RTC subsystem upper
API, rtc-device.ops_lock
has been required sucessfully, If continue to require the
rtc-device.ops_lock in ' rp5c01_read_time()',
the 'lock' will cannot be get, dead lock occurs.
>
> diff --git a/drivers/rtc/rtc-rp5c01.c b/drivers/rtc/rtc-rp5c01.c
> index a95f733..36eb661 100644
> --- a/drivers/rtc/rtc-rp5c01.c
> +++ b/drivers/rtc/rtc-rp5c01.c
> @@ -63,6 +63,8 @@ enum {
> struct rp5c01_priv {
> u32 __iomem *regs;
> struct rtc_device *rtc;
> + spinlock_t lock; /* against concurrent RTC/NVRAM access */
> + struct bin_attribute nvram_attr;
> };
>
> static inline unsigned int rp5c01_read(struct rp5c01_priv *priv,
> @@ -92,6 +94,7 @@ static int rp5c01_read_time(struct device *dev, struct rtc_time *tm)
> {
> struct rp5c01_priv *priv = dev_get_drvdata(dev);
>
> + spin_lock_irq(&priv->lock);
> rp5c01_lock(priv);
>
> tm->tm_sec = rp5c01_read(priv, RP5C01_10_SECOND) * 10 +
> @@ -111,6 +114,7 @@ static int rp5c01_read_time(struct device *dev, struct rtc_time *tm)
> tm->tm_year += 100;
>
> rp5c01_unlock(priv);
> + spin_unlock_irq(&priv->lock);
>
> return rtc_valid_tm(tm);
> }
> @@ -119,6 +123,7 @@ static int rp5c01_set_time(struct device *dev, struct rtc_time *tm)
> {
> struct rp5c01_priv *priv = dev_get_drvdata(dev);
>
> + spin_lock_irq(&priv->lock);
> rp5c01_lock(priv);
>
> rp5c01_write(priv, tm->tm_sec / 10, RP5C01_10_SECOND);
> @@ -139,6 +144,7 @@ static int rp5c01_set_time(struct device *dev, struct rtc_time *tm)
> rp5c01_write(priv, tm->tm_year % 10, RP5C01_1_YEAR);
>
> rp5c01_unlock(priv);
> + spin_unlock_irq(&priv->lock);
> return 0;
> }
>
> @@ -147,6 +153,72 @@ static const struct rtc_class_ops rp5c01_rtc_ops = {
> .set_time = rp5c01_set_time,
> };
>
> +
> +/*
> + * The NVRAM is organized as 2 blocks of 13 nibbles of 4 bits.
> + * We provide access to them like AmigaOS does: the high nibble of each 8-bit
> + * byte is stored in BLOCK10, the low nibble in BLOCK11.
> + */
> +
> +static ssize_t rp5c01_nvram_read(struct file *filp, struct kobject *kobj,
> + struct bin_attribute *bin_attr,
> + char *buf, loff_t pos, size_t size)
> +{
> + struct device *dev = container_of(kobj, struct device, kobj);
> + struct rp5c01_priv *priv = dev_get_drvdata(dev);
> + ssize_t count;
> +
> + spin_lock_irq(&priv->lock);
> +
> + for (count = 0; size > 0 && pos < RP5C01_MODE; count++, size--) {
> + u8 data;
> +
> + rp5c01_write(priv,
> + RP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK10,
> + RP5C01_MODE);
> + data = rp5c01_read(priv, pos) << 4;
> + rp5c01_write(priv,
> + RP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK11,
> + RP5C01_MODE);
> + data |= rp5c01_read(priv, pos++);
> + rp5c01_write(priv, RP5C01_MODE_TIMER_EN | RP5C01_MODE_MODE01,
> + RP5C01_MODE);
> + *buf++ = data;
> + }
> +
> + spin_unlock_irq(&priv->lock);
> + return count;
> +}
> +
> +static ssize_t rp5c01_nvram_write(struct file *filp, struct kobject *kobj,
> + struct bin_attribute *bin_attr,
> + char *buf, loff_t pos, size_t size)
> +{
> + struct device *dev = container_of(kobj, struct device, kobj);
> + struct rp5c01_priv *priv = dev_get_drvdata(dev);
> + ssize_t count;
> +
> + spin_lock_irq(&priv->lock);
> +
> + for (count = 0; size > 0 && pos < RP5C01_MODE; count++, size--) {
> + u8 data = *buf++;
> +
> + rp5c01_write(priv,
> + RP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK10,
> + RP5C01_MODE);
> + rp5c01_write(priv, data >> 4, pos);
> + rp5c01_write(priv,
> + RP5C01_MODE_TIMER_EN | RP5C01_MODE_RAM_BLOCK11,
> + RP5C01_MODE);
> + rp5c01_write(priv, data & 0xf, pos++);
> + rp5c01_write(priv, RP5C01_MODE_TIMER_EN | RP5C01_MODE_MODE01,
> + RP5C01_MODE);
> + }
> +
> + spin_unlock_irq(&priv->lock);
> + return count;
> +}
> +
> static int __init rp5c01_rtc_probe(struct platform_device *dev)
> {
> struct resource *res;
> @@ -168,6 +240,15 @@ static int __init rp5c01_rtc_probe(struct platform_device *dev)
> goto out_free_priv;
> }
>
> + sysfs_bin_attr_init(&priv->nvram_attr);
> + priv->nvram_attr.attr.name = "nvram";
> + priv->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
> + priv->nvram_attr.read = rp5c01_nvram_read;
> + priv->nvram_attr.write = rp5c01_nvram_write;
> + priv->nvram_attr.size = RP5C01_MODE;
> +
> + spin_lock_init(&priv->lock);
> +
> rtc = rtc_device_register("rtc-rp5c01", &dev->dev, &rp5c01_rtc_ops,
> THIS_MODULE);
> if (IS_ERR(rtc)) {
> @@ -177,8 +258,15 @@ static int __init rp5c01_rtc_probe(struct platform_device *dev)
>
> priv->rtc = rtc;
> platform_set_drvdata(dev, priv);
> +
> + error = sysfs_create_bin_file(&dev->dev.kobj, &priv->nvram_attr);
> + if (error)
> + goto out_unregister;
> +
> return 0;
>
> +out_unregister:
> + rtc_device_unregister(rtc);
> out_unmap:
> iounmap(priv->regs);
> out_free_priv:
> @@ -190,6 +278,7 @@ static int __exit rp5c01_rtc_remove(struct platform_device *dev)
> {
> struct rp5c01_priv *priv = platform_get_drvdata(dev);
>
> + sysfs_remove_bin_file(&dev->dev.kobj, &priv->nvram_attr);
> rtc_device_unregister(priv->rtc);
> iounmap(priv->regs);
> kfree(priv);
> --
> 1.7.0.4
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
>
> --
> You received this message because you are subscribed to "rtc-linux".
> Membership options at http://groups.google.com/group/rtc-linux .
> Please read http://groups.google.com/group/rtc-linux/web/checklist
> before submitting a driver.
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