Instead of adding a binary sysfs attribute from the driver, use the
core to register an nvmem device. This allows to use the in-kernel
interface to access the nvram.

Signed-off-by: Alexandre Belloni <alexandre.bell...@bootlin.com>
---
 drivers/rtc/rtc-cmos.c | 73 +++++++++++++++++++++-----------------------------
 1 file changed, 30 insertions(+), 43 deletions(-)

diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index e6393e784d0c..b8ec6009171a 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -541,11 +541,10 @@ static const struct rtc_class_ops cmos_rtc_ops = {
 
 #define NVRAM_OFFSET   (RTC_REG_D + 1)
 
-static ssize_t
-cmos_nvram_read(struct file *filp, struct kobject *kobj,
-               struct bin_attribute *attr,
-               char *buf, loff_t off, size_t count)
+static int cmos_nvram_read(void *priv, unsigned int off, void *val,
+                          size_t count)
 {
+       unsigned char *buf = val;
        int     retval;
 
        off += NVRAM_OFFSET;
@@ -563,16 +562,13 @@ cmos_nvram_read(struct file *filp, struct kobject *kobj,
        return retval;
 }
 
-static ssize_t
-cmos_nvram_write(struct file *filp, struct kobject *kobj,
-               struct bin_attribute *attr,
-               char *buf, loff_t off, size_t count)
+static int cmos_nvram_write(void *priv, unsigned int off, void *val,
+                           size_t count)
 {
-       struct cmos_rtc *cmos;
+       struct cmos_rtc *cmos = priv;
+       unsigned char   *buf = val;
        int             retval;
 
-       cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
-
        /* NOTE:  on at least PCs and Ataris, the boot firmware uses a
         * checksum on part of the NVRAM data.  That's currently ignored
         * here.  If userspace is smart enough to know what fields of
@@ -598,17 +594,6 @@ cmos_nvram_write(struct file *filp, struct kobject *kobj,
        return retval;
 }
 
-static struct bin_attribute nvram = {
-       .attr = {
-               .name   = "nvram",
-               .mode   = S_IRUGO | S_IWUSR,
-       },
-
-       .read   = cmos_nvram_read,
-       .write  = cmos_nvram_write,
-       /* size gets set up later */
-};
-
 /*----------------------------------------------------------------*/
 
 static struct cmos_rtc cmos_rtc;
@@ -675,6 +660,14 @@ cmos_do_probe(struct device *dev, struct resource *ports, 
int rtc_irq)
        unsigned char                   rtc_control;
        unsigned                        address_space;
        u32                             flags = 0;
+       struct nvmem_config nvmem_cfg = {
+               .name = "cmos_nvram",
+               .word_size = 1,
+               .stride = 1,
+               .reg_read = cmos_nvram_read,
+               .reg_write = cmos_nvram_write,
+               .priv = &cmos_rtc,
+       };
 
        /* there can be only one ... */
        if (cmos_rtc.dev)
@@ -813,32 +806,28 @@ cmos_do_probe(struct device *dev, struct resource *ports, 
int rtc_irq)
                }
        }
 
-       /* export at least the first block of NVRAM */
-       nvram.size = address_space - NVRAM_OFFSET;
-       retval = sysfs_create_bin_file(&dev->kobj, &nvram);
-       if (retval < 0) {
-               dev_dbg(dev, "can't create nvram file? %d\n", retval);
-               goto cleanup2;
-       }
-
        cmos_rtc.rtc->ops = &cmos_rtc_ops;
+       cmos_rtc.rtc->nvram_old_abi = true;
        retval = rtc_register_device(cmos_rtc.rtc);
        if (retval)
-               goto cleanup3;
+               goto cleanup2;
 
-       dev_info(dev, "%s%s, %zd bytes nvram%s\n",
-               !is_valid_irq(rtc_irq) ? "no alarms" :
-                       cmos_rtc.mon_alrm ? "alarms up to one year" :
-                       cmos_rtc.day_alrm ? "alarms up to one month" :
-                       "alarms up to one day",
-               cmos_rtc.century ? ", y3k" : "",
-               nvram.size,
-               is_hpet_enabled() ? ", hpet irqs" : "");
+       /* export at least the first block of NVRAM */
+       nvmem_cfg.size = address_space - NVRAM_OFFSET;
+       if (rtc_nvmem_register(cmos_rtc.rtc, &nvmem_cfg))
+               dev_err(dev, "nvmem registration failed\n");
+
+       dev_info(dev, "%s%s, %d bytes nvram%s\n",
+                !is_valid_irq(rtc_irq) ? "no alarms" :
+                cmos_rtc.mon_alrm ? "alarms up to one year" :
+                cmos_rtc.day_alrm ? "alarms up to one month" :
+                "alarms up to one day",
+                cmos_rtc.century ? ", y3k" : "",
+                nvmem_cfg.size,
+                is_hpet_enabled() ? ", hpet irqs" : "");
 
        return 0;
 
-cleanup3:
-       sysfs_remove_bin_file(&dev->kobj, &nvram);
 cleanup2:
        if (is_valid_irq(rtc_irq))
                free_irq(rtc_irq, cmos_rtc.rtc);
@@ -867,8 +856,6 @@ static void cmos_do_remove(struct device *dev)
 
        cmos_do_shutdown(cmos->irq);
 
-       sysfs_remove_bin_file(&dev->kobj, &nvram);
-
        if (is_valid_irq(cmos->irq)) {
                free_irq(cmos->irq, cmos->rtc);
                hpet_unregister_irq_handler(cmos_interrupt);
-- 
2.16.1

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