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rtc: rtc-rs5c313: Fix late hardware init

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rs5c313_rtc_init() calls platform_driver_register(), and initializes the
hardware.  This is wrong because of two reasons:
  1. As soon as the driver has been registered, the device may be
     probed.  If devm_rtc_device_register() is called before hardware
     initialization, reading the current time will fail:

	rs5c313 rs5c313: rs5c313_rtc_read_time: timeout error
	rs5c313 rs5c313: registered as rtc0
	rs5c313 rs5c313: rs5c313_rtc_read_time: timeout error
	rs5c313 rs5c313: hctosys: unable to read the hardware clock

  2. If the platform device does not exist, the driver will still write
     to a hardware device that may not be present.

Fix this by moving the hardware initialization sequence to the driver's
.probe() method.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200814110731.29029-3-geert+renesas@glider.be
This commit is contained in:
Geert Uytterhoeven 2020-08-14 13:07:30 +02:00 committed by Alexandre Belloni
parent fc9656a370
commit f65e727464
1 changed files with 8 additions and 12 deletions
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20
drivers/rtc/rtc-rs5c313.c
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@ -366,8 +366,13 @@ static const struct rtc_class_ops rs5c313_rtc_ops = {
static int rs5c313_rtc_probe(struct platform_device *pdev) static int rs5c313_rtc_probe(struct platform_device *pdev)
{ {
struct rtc_device *rtc = devm_rtc_device_register(&pdev->dev, "rs5c313", struct rtc_device *rtc;
&rs5c313_rtc_ops, THIS_MODULE);
rs5c313_init_port();
rs5c313_check_xstp_bit();
rtc = devm_rtc_device_register(&pdev->dev, "rs5c313", &rs5c313_rtc_ops,
THIS_MODULE);
return PTR_ERR_OR_ZERO(rtc); return PTR_ERR_OR_ZERO(rtc);
} }
@ -381,16 +386,7 @@ static struct platform_driver rs5c313_rtc_platform_driver = {
static int __init rs5c313_rtc_init(void) static int __init rs5c313_rtc_init(void)
{ {
int err; return platform_driver_register(&rs5c313_rtc_platform_driver);
err = platform_driver_register(&rs5c313_rtc_platform_driver);
if (err)
return err;
rs5c313_init_port();
rs5c313_check_xstp_bit();
return 0;
} }
static void __exit rs5c313_rtc_exit(void) static void __exit rs5c313_rtc_exit(void)