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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: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
This commit is contained in:
H Hartley Sweeten 2017-02-10 11:11:57 -07:00 committed by Alexandre Belloni
parent 8057c86d43
commit b180cf8b0b
1 changed files with 41 additions and 0 deletions
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41
drivers/rtc/rtc-m48t86.c
View File

@ -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);