tiny4412 驅動 （17）RTC驅動

裝置樹

vim arch/arm/boot/dts/exynos4.dtsi

        rtc: [email protected] {
                compatible = "samsung,s3c6410-rtc";
                reg = <0x10070000 0x100>;
                interrupt-parent = <&pmu_system_controller>;
                interrupts = <GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH>,
                             <GIC_SPI 45 IRQ_TYPE_LEVEL_HIGH>;
                clocks = <&clock CLK_RTC>;
                clock-names = "rtc";
                status = "disabled";
        };


vim arch/arm/boot/dts/exynos4412-tiny4412.dts

&rtc {
        status = "okay";
};
           

menuconfig

Device Drivers > 
    Real Time Clock->
        <*>   Samsung S3C series SoC RTC
           

然而啟動日志裡面看到

[    1.574221] s3c-rtc 10070000.rtc: failed to find rtc source clock
[    1.578937] s3c-rtc: probe of 10070000.rtc failed with error -2
[    1.966342] hctosys: unable to open rtc device (rtc0)
           

drivers/rtc/rtc-s3c.c:550:					"failed to find rtc source clock\n");
           

static int s3c_rtc_probe(struct platform_device *pdev)
{
    ...
    	if (info->data->needs_src_clk) {
		info->rtc_src_clk = devm_clk_get(&pdev->dev, "rtc_src");
		if (IS_ERR(info->rtc_src_clk)) {
			ret = PTR_ERR(info->rtc_src_clk);
			if (ret != -EPROBE_DEFER)
				dev_err(&pdev->dev,
					"failed to find rtc source clock\n");
			else
				dev_dbg(&pdev->dev,
					"probe deferred due to missing rtc src clk\n");
			goto err_src_clk;
		}
		ret = clk_prepare_enable(info->rtc_src_clk);
		if (ret)
			goto err_src_clk;
	}

    ...
}
           

其中info->data是：

static struct s3c_rtc_data const s3c6410_rtc_data = {
	.max_user_freq		= 32768,
	.needs_src_clk		= true,           // 采用外部32.768K的晶振，不需要從MCLK得到額外時鐘
	.irq_handler		= s3c6410_rtc_irq,
	.set_freq		= s3c6410_rtc_setfreq,
	.enable_tick		= s3c6410_rtc_enable_tick,
	.save_tick_cnt		= s3c6410_rtc_save_tick_cnt,
	.restore_tick_cnt	= s3c6410_rtc_restore_tick_cnt,
	.enable			= s3c24xx_rtc_enable,
	.disable		= s3c6410_rtc_disable,
};

static const struct of_device_id s3c_rtc_dt_match[] = {
    ...
    {
		.compatible = "samsung,s3c2443-rtc",
		.data = &s3c2443_rtc_data,
	}, {
		.compatible = "samsung,s3c6410-rtc",
		.data = &s3c6410_rtc_data,
	}, 
	{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, s3c_rtc_dt_match);

static struct platform_driver s3c_rtc_driver = {
	.probe		= s3c_rtc_probe,
	.remove		= s3c_rtc_remove,
	.driver		= {
		.name	= "s3c-rtc",
		.pm	= &s3c_rtc_pm_ops,
		.of_match_table	= of_match_ptr(s3c_rtc_dt_match),
	},
};
           

最後

啟動日志

[    1.574044] s3c-rtc 10070000.rtc: rtc disabled, re-enabling
[    1.578363] s3c-rtc 10070000.rtc: warning: invalid RTC value so initializing it
[    1.585656] rtc rtc0: invalid alarm value: 1900-1-1 0:0:0
[    1.591240] s3c-rtc 10070000.rtc: rtc core: registered s3c as rtc0
[    1.971626] s3c-rtc 10070000.rtc: setting system clock to 2000-01-01 00:00:00 UTC (946684800)
           

[[email protected] ]# ls /dev/rtc0 
/dev/rtc0
[[email protected] ]# 
[[email protected] ]# date -s "2019-11-11 20:33:30"
Mon Nov 11 20:33:30 UTC 2019
[[email protected] ]# hwclock
Sat Jan  1 00:02:45 2000  0.000000 seconds
[[email protected] ]# hwclock -w
[[email protected] ]# 
[root@tiny4412 ]# hwclock
Mon Nov 11 20:33:43 2019  0.000000 seconds