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Commit b180cf8b authored by H Hartley Sweeten's avatar H Hartley Sweeten Committed by Alexandre Belloni
Browse files

rtc: m48t86: add NVRAM support 



This RTC has 114 bytes of NVRAM. Provide access to it via a binary
sysfs 'nvram' attribute file.

Signed-off-by: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 8057c86d

drivers/rtc/rtc-m48t86.c

+41 −0
Original line number Diff line number Diff line
@@ -38,6 +38,8 @@ 
#define M48T86_C		0x0c

#define M48T86_D		0x0d

#define M48T86_D_VRT		BIT(7)

#define M48T86_NVRAM(x)		(0x0e + (x))

#define M48T86_NVRAM_LEN	114



struct m48t86_rtc_info {

	void __iomem *index_reg;
@@ -170,6 +172,35 @@ static const struct rtc_class_ops m48t86_rtc_ops = { 
	.proc		= m48t86_rtc_proc,

};



static ssize_t m48t86_nvram_read(struct file *filp, struct kobject *kobj,

				 struct bin_attribute *attr,

				 char *buf, loff_t off, size_t count)

{

	struct device *dev = kobj_to_dev(kobj);

	unsigned int i;



	for (i = 0; i < count; i++)

		buf[i] = m48t86_readb(dev, M48T86_NVRAM(off + i));



	return count;

}



static ssize_t m48t86_nvram_write(struct file *filp, struct kobject *kobj,

				  struct bin_attribute *attr,

				  char *buf, loff_t off, size_t count)

{

	struct device *dev = kobj_to_dev(kobj);

	unsigned int i;



	for (i = 0; i < count; i++)

		m48t86_writeb(dev, buf[i], M48T86_NVRAM(off + i));



	return count;

}



static BIN_ATTR(nvram, 0644, m48t86_nvram_read, m48t86_nvram_write,

		M48T86_NVRAM_LEN);



static int m48t86_rtc_probe(struct platform_device *pdev)

{

	struct m48t86_rtc_info *info;
@@ -210,6 +241,15 @@ static int m48t86_rtc_probe(struct platform_device *pdev) 
	dev_info(&pdev->dev, "battery %s\n",

		 (reg & M48T86_D_VRT) ? "ok" : "exhausted");



	if (device_create_bin_file(&pdev->dev, &bin_attr_nvram))

		dev_err(&pdev->dev, "failed to create nvram sysfs entry\n");



	return 0;

}



static int m48t86_rtc_remove(struct platform_device *pdev)

{

	device_remove_bin_file(&pdev->dev, &bin_attr_nvram);

	return 0;

}
@@ -218,6 +258,7 @@ static struct platform_driver m48t86_rtc_platform_driver = { 
		.name	= "rtc-m48t86",

	},

	.probe		= m48t86_rtc_probe,

	.remove		= m48t86_rtc_remove,

};



module_platform_driver(m48t86_rtc_platform_driver);