Re: [PATCH v2 1/2] rtc: Add driver for Sunplus SP7021

From: Mateusz Jończyk
Date: Fri Nov 19 2021 - 17:28:27 EST

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Hello,

W dniu 09.11.2021 o 07:38, Vincent Shih pisze:

> Add driver for Sunplus SP7021

If I understand correctly, SP7021 is the name of the SoC, not of the RTC. So the commit subject should be something like "Add driver for RTC in Sunplus SP7021".

> Signed-off-by: Vincent Shih <vincent.shih@xxxxxxxxxxx>
> ---
> Changes in v2:
> - Addressed the comments from Mr. Philipp Zabel
> - Addressed the comments from Mr. Randy Dunlap
> - Addressed the comments from Mr. Alexandre Belloni
> - Sorted the files in Makefile
>
> MAINTAINERS | 6 +
> drivers/rtc/Kconfig | 11 ++
> drivers/rtc/Makefile | 1 +
> drivers/rtc/rtc-sunplus.c | 370 ++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 388 insertions(+)
> create mode 100644 drivers/rtc/rtc-sunplus.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3b79fd4..6c1a535 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -17945,6 +17945,12 @@ L: netdev@xxxxxxxxxxxxxxx
> S: Maintained
> F: drivers/net/ethernet/dlink/sundance.c
>
> +SUNPLUS RTC DRIVER
> +M: Vincent Shih <vincent.shih@xxxxxxxxxxx>
> +L: linux-rtc@xxxxxxxxxxxxxxx
> +S: Maintained
> +F: drivers/rtc/rtc-sunplus.c
> +
> SUPERH
> M: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
> M: Rich Felker <dalias@xxxxxxxx>
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index e1bc521..7ca6765 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -1028,6 +1028,17 @@ config RTC_DRV_DS1685_FAMILY
> This driver can also be built as a module. If so, the module
> will be called rtc-ds1685.
>
> +config RTC_DRV_SUNPLUS
> + bool "Sunplus SP7021 RTC"
> + depends on SOC_SP7021
> + help
> + Say 'yes' to get support for Sunplus SP7021 real-time clock
> + (RTC) for industrial applications.
> +

Maybe:
"Say 'yes' to get support for the real-time clock present in Sunplus SP7021 - a SoC for industrial applications."

> + It provides RTC status check, timer/alarm functionalities,
> + user data reservation only with battery with voltage over 2.5V,

I'm sorry, but I don't understand. What is "user data reservation only"?

> + RTC power status check and battery charge.
> +
> choice
> prompt "Subtype"
> depends on RTC_DRV_DS1685_FAMILY
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 5ceeafe..93cb4b2 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -164,6 +164,7 @@ obj-$(CONFIG_RTC_DRV_STM32) += rtc-stm32.o
> obj-$(CONFIG_RTC_DRV_STMP) += rtc-stmp3xxx.o
> obj-$(CONFIG_RTC_DRV_SUN4V) += rtc-sun4v.o
> obj-$(CONFIG_RTC_DRV_SUN6I) += rtc-sun6i.o
> +obj-$(CONFIG_RTC_DRV_SUNPLUS) += rtc-sunplus.o
> obj-$(CONFIG_RTC_DRV_SUNXI) += rtc-sunxi.o
> obj-$(CONFIG_RTC_DRV_TEGRA) += rtc-tegra.o
> obj-$(CONFIG_RTC_DRV_TEST) += rtc-test.o
> diff --git a/drivers/rtc/rtc-sunplus.c b/drivers/rtc/rtc-sunplus.c
> new file mode 100644
> index 0000000..73c400d
> --- /dev/null
> +++ b/drivers/rtc/rtc-sunplus.c
> @@ -0,0 +1,370 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +/* */
> +/* The RTC driver for Sunplus SP7021 */
> +/* */
> +/* Copyright (C) 2019 Sunplus Technology Inc., All rights reseerved. */
> +/* */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/ktime.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/reset.h>
> +#include <linux/rtc.h>
> +#include <linux/platform_device.h>
> +
> +#define RTC_REG_NAME "rtc_reg"
> +
> +#define RTC_CTRL 0x40
> +#define TIMER_FREEZE (0x1 << 5)
> +#define TIMER_FREEZE_MASK (1 << (5 + 16))
> +#define DIS_SYS_RST_RTC (0x1 << 4)
> +#define DIS_SYS_RST_RTC_MASK (1 << (4 + 16))
> +#define RTC32K_MODE_RESET (0x1 << 3)
> +#define RTC32K_MODE_RESET_MASK (1 << (3 + 16))
> +#define ALARM_EN_OVERDUE (0x1 << 2)
> +#define ALARM_EN_OVERDUE_MASK (1 << (2 + 16))
> +#define ALARM_EN_PMC (0x1 << 1)
> +#define ALARM_EN_PMC_MASK (1 << (1 + 16))
> +#define ALARM_EN (0x1 << 0)
> +#define ALARM_EN_MASK (1 << (0 + 16))
> +#define RTC_TIMER_OUT 0x44
> +#define RTC_DIVIDER 0x48
> +#define RTC_TIMER_SET 0x4c
> +#define RTC_ALARM_SET 0x50
> +#define RTC_USER_DATA 0x54
> +#define RTC_RESET_RECORD 0x58
> +#define RTC_BATTERY_CTRL 0x5c
> +#define BAT_CHARGE_RSEL_2K_OHM (0x0 << 2)
> +#define BAT_CHARGE_RSEL_250_OHM (0x1 << 2)
> +#define BAT_CHARGE_RSEL_50_OHM (0x2 << 2)
> +#define BAT_CHARGE_RSEL_0_OHM (0x3 << 2)
> +#define BAT_CHARGE_RSEL_MASK (0x3 << (2 + 16))
> +#define BAT_CHARGE_DSEL_ON (0x0 << 1)
> +#define BAT_CHARGE_DSEL_OFF (0x1 << 1)
> +#define BAT_CHARGE_DSEL_MASK (0x1 << (1 + 16))
> +#define BAT_CHARGE_EN (0x1 << 0)
> +#define BAT_CHARGE_EN_MASK (0x1 << (0 + 16))
> +#define RTC_TRIM_CTRL 0x60
> +
> +struct sunplus_rtc {
> + struct clk *rtcclk;
> + struct reset_control *rstc;
> + void __iomem *base;
> + u32 ohms;
> +};
> +
> +struct sunplus_rtc sp_rtc;
> +
> +static void sp_get_seconds(unsigned long *secs)
> +{
> + *secs = (unsigned long)readl(sp_rtc.base + RTC_TIMER_OUT);
> +}
> +
> +static void sp_set_seconds(unsigned long secs)
> +{
> + writel((u32)secs, sp_rtc.base + RTC_TIMER_SET);
> +}
> +
> +static int sp_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> + unsigned long secs;
> +
> + sp_get_seconds(&secs);
> + rtc_time64_to_tm(secs, tm);
> + dev_dbg(dev, "%s: RTC date/time to %d-%d-%d, %02d:%02d:%02d.\r\n",
> + __func__, tm->tm_mday, tm->tm_mon + 1, tm->tm_year,
> + tm->tm_hour, tm->tm_min, tm->tm_sec);
> +
> + return rtc_valid_tm(tm);
> +}

Is it necessary to call rtc_valid_tm(tm) here?

> +
> +int sp_rtc_get_time(struct rtc_time *tm)
> +{
> + unsigned long secs;
> +
> + sp_get_seconds(&secs);
> + rtc_time64_to_tm(secs, tm);
> +
> + return 0;
> +}
> +

This function looks unused.

> +static int sp_rtc_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> + dev_dbg(&pdev->dev, "[RTC] Debug: %s(%d)\n", __func__, __LINE__);
> +
> + // Keep RTC from system reset
> + writel(DIS_SYS_RST_RTC_MASK | DIS_SYS_RST_RTC, sp_rtc.base + RTC_CTRL);
> +
> + return 0;
> +}
> +
> +static int sp_rtc_resume(struct platform_device *pdev)
> +{
> + /* */
> + /* Because RTC is still powered during suspend, */
> + /* there is nothing to do here. */
> + /* */
> + dev_dbg(&pdev->dev, "[RTC] Debug: %s(%d)\n", __func__, __LINE__);
> +
> + // Keep RTC from system reset
> + writel(DIS_SYS_RST_RTC_MASK | DIS_SYS_RST_RTC, sp_rtc.base + RTC_CTRL);
> +
> + return 0;
> +}
> +
> +static int sp_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> + unsigned long secs;
> +
> + secs = rtc_tm_to_time64(tm);
> + dev_dbg(dev, "%s, secs = %lu\n", __func__, secs);
> + sp_set_seconds(secs);
> +
> + return 0;
> +}
> +
> +static int sp_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> + unsigned long alarm_time;
> +
> + alarm_time = rtc_tm_to_time64(&alrm->time);
> + dev_dbg(dev, "%s, alarm_time: %u\n", __func__, (u32)(alarm_time));
> + writel((u32)alarm_time, sp_rtc.base + RTC_ALARM_SET);
> +
> + return 0;
> +}
> +
> +static int sp_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> + unsigned int alarm_time;
> +
> + alarm_time = readl(sp_rtc.base + RTC_ALARM_SET);
> + dev_dbg(dev, "%s, alarm_time: %u\n", __func__, alarm_time);
> +
> + if (alarm_time == 0) {
> + // alarm is disabled
> + alrm->enabled = 0;
> + } else {
> + // alarm is enabled
> + alrm->enabled = 1;
> + rtc_time64_to_tm((unsigned long)(alarm_time), &alrm->time);
> + }
> +
> + return 0;
> +}
> +
> +static int sp_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
> +{
> + if (enabled)
> + writel((TIMER_FREEZE_MASK | DIS_SYS_RST_RTC_MASK | RTC32K_MODE_RESET_MASK |
> + ALARM_EN_OVERDUE_MASK | ALARM_EN_PMC_MASK | ALARM_EN_MASK) |
> + (DIS_SYS_RST_RTC | ALARM_EN_OVERDUE | ALARM_EN_PMC |
> + ALARM_EN), sp_rtc.base + RTC_CTRL);
> + else
> + writel((ALARM_EN_OVERDUE_MASK | ALARM_EN_PMC_MASK | ALARM_EN_MASK) | 0x0,
> + sp_rtc.base + RTC_CTRL);
> +
> + return 0;
> +}
> +
> +static const struct rtc_class_ops sp_rtc_ops = {
> + .read_time = sp_rtc_read_time,
> + .set_time = sp_rtc_set_time,
> + .set_alarm = sp_rtc_set_alarm,
> + .read_alarm = sp_rtc_read_alarm,
> + .alarm_irq_enable = sp_rtc_alarm_irq_enable,
> +};
> +
> +static irqreturn_t rtc_irq_handler(int irq, void *dev_id)
> +{

Perhaps rename to "sp_rtc_irq_handler".

> + struct platform_device *plat_dev = dev_id;
> + struct rtc_device *rtc = platform_get_drvdata(plat_dev);
> +
> + rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
> + dev_dbg(&plat_dev->dev, "[RTC] ALARM INT\n");
> +
> + return IRQ_HANDLED;
> +}
> +
> +/* ---------------------------------------------------------------------------------------------- */
> +/* bat_charge_rsel bat_charge_dsel bat_charge_en Remarks */
> +/* x x 0 Disable */
> +/* 0 0 1 0.86mA (2K Ohm with diode) */
> +/* 1 0 1 1.81mA (250 Ohm with diode) */
> +/* 2 0 1 2.07mA (50 Ohm with diode) */
> +/* 3 0 1 16.0mA (0 Ohm with diode) */
> +/* 0 1 1 1.36mA (2K Ohm without diode) */
> +/* 1 1 1 3.99mA (250 Ohm without diode) */
> +/* 2 1 1 4.41mA (50 Ohm without diode) */
> +/* 3 1 1 16.0mA (0 Ohm without diode) */
> +/* ---------------------------------------------------------------------------------------------- */
> +static void sp_rtc_set_trickle_charger(struct device dev)
> +{
> + int ret;
> + u32 rsel;
> +
> + ret = of_property_read_u32(dev.of_node, "trickle-resistor-ohms", &sp_rtc.ohms);
> + if (ret)
> + return;
> +
> + switch (sp_rtc.ohms) {
> + case 2000:
> + rsel = BAT_CHARGE_RSEL_2K_OHM;
> + break;
> + case 250:
> + rsel = BAT_CHARGE_RSEL_250_OHM;
> + break;
> + case 50:
> + rsel = BAT_CHARGE_RSEL_50_OHM;
> + break;
> + case 0:
> + rsel = BAT_CHARGE_RSEL_0_OHM;
> + break;
> + default:
> + return;

I think that some warning message should be printed here.

> + }
> +
> + writel(BAT_CHARGE_RSEL_MASK | rsel, sp_rtc.base + RTC_BATTERY_CTRL);
> +
> + ret = of_property_read_bool(dev.of_node, "trickle-diode-disable");
> + if (ret)
> + writel(BAT_CHARGE_DSEL_MASK | BAT_CHARGE_DSEL_OFF, sp_rtc.base + RTC_BATTERY_CTRL);
> + else
> + writel(BAT_CHARGE_DSEL_MASK | BAT_CHARGE_DSEL_ON, sp_rtc.base + RTC_BATTERY_CTRL);
> +
> + writel(BAT_CHARGE_EN_MASK | BAT_CHARGE_EN, sp_rtc.base + RTC_BATTERY_CTRL);
> +}
> +
> +static int sp_rtc_probe(struct platform_device *plat_dev)
> +{
> + struct rtc_device *rtc;
> + struct resource *res;
> + const struct rtc_class_ops *rtc_ops;
> + void __iomem *reg_base;
> + int ret, irq;
> +
> + memset(&sp_rtc, 0, sizeof(sp_rtc));
> +
> + // find and map our resources
> + res = platform_get_resource_byname(plat_dev, IORESOURCE_MEM, RTC_REG_NAME);
> +
> + if (res) {
> + dev_dbg(&plat_dev->dev, "res = 0x%x\n", res->start);
> +
> + reg_base = devm_ioremap_resource(&plat_dev->dev, res);
> + if (IS_ERR(reg_base)) {
> + dev_err(&plat_dev->dev, "%s devm_ioremap_resource fail\n", RTC_REG_NAME);
> + return PTR_ERR(reg_base);
> + }
> +
> + dev_dbg(&plat_dev->dev, "reg_base = 0x%lx\n", (unsigned long)reg_base);
> + }

Handle correctly the case when (res == NULL) - currently the function keeps running with undefined value of reg_base.

> +
> + sp_rtc.base = reg_base;
> + rtc_ops = &sp_rtc_ops;
> +
> + // Keep RTC from system reset
> + writel(DIS_SYS_RST_RTC_MASK | DIS_SYS_RST_RTC, sp_rtc.base + RTC_CTRL);

I would suggest to extract the above line into a function as it appears three times in this file.

Note: I'm quite new to kernel development, I also did not review this patch throughly.

Greetings,
Mateusz

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