[PATCH] power: pmic: pca9450: Add support for system reset

[Paul Geurts]

> The family of PCA9450 PMICs have the ability to perform system resets.
> Restarting via PMIC is preferred method of restarting the system as all
> the peripherals are brought to a know state after a power-cycle. The
> PCA9450 features a cold restart procedure which is initiated by an I2C
> command 0x14 to the SW_RST register.
> 
> Support in Linux for restarting via PCA9450 PMIC has been added by
> Linux commit 6157e62b07d9 ("regulator: pca9450: Add restart handler").
> 
> Now add support for it also in the U-Boot via sysreset framework.
> 
> Signed-off-by: Primoz Fiser <primoz.fiser at norik.com>
> ---
>  drivers/power/pmic/pca9450.c | 42 ++++++++++++++++++++++++++++++++++++
>  include/power/pca9450.h      |  2 ++
>  2 files changed, 44 insertions(+)
> 
> diff --git a/drivers/power/pmic/pca9450.c b/drivers/power/pmic/pca9450.c
> index 9d875f8bdbe8..abc39d0a1946 100644
> --- a/drivers/power/pmic/pca9450.c
> +++ b/drivers/power/pmic/pca9450.c
> @@ -7,15 +7,18 @@
>  #include <errno.h>
>  #include <dm.h>
>  #include <dm/device_compat.h>
> +#include <dm/lists.h>
>  #include <i2c.h>
>  #include <linux/err.h>
>  #include <log.h>
>  #include <asm/global_data.h>
>  #include <asm-generic/gpio.h>
> +#include <linux/delay.h>
>  #include <linux/printk.h>
>  #include <power/pmic.h>
>  #include <power/regulator.h>
>  #include <power/pca9450.h>
> +#include <sysreset.h>
>  
>  DECLARE_GLOBAL_DATA_PTR;
>  
> @@ -101,6 +104,14 @@ static int pca9450_probe(struct udevice *dev)
>  		}
>  	}
>  
> +	if (CONFIG_IS_ENABLED(SYSRESET)) {
> +		ret = device_bind_driver_to_node(dev, "pca9450_sysreset",
> +						 "pca9450_sysreset",
> +						 dev_ofnode(dev), NULL);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	if (ofnode_read_bool(dev_ofnode(dev), "nxp,wdog_b-warm-reset"))
>  		reset_ctrl = PCA9450_PMIC_RESET_WDOG_B_CFG_WARM;
>  	else
> @@ -134,3 +145,34 @@ U_BOOT_DRIVER(pmic_pca9450) = {
>  	.ops = &pca9450_ops,
>  	.priv_auto = sizeof(struct pca9450_priv),
>  };
> +
> +#ifdef CONFIG_SYSRESET
> +static int pca9450_sysreset_request(struct udevice *dev, enum sysreset_t type)
> +{
> +	u8 cmd = PCA9450_SW_RST_COLD_RST;
> +
> +	if (type != SYSRESET_COLD)

The PCA9450 calls it "cold reset", but it is technically SYSRESET_POWER.
There is no option for it in the sysreset do_reset, but maybe there should be.

> +		return -EPROTONOSUPPORT;
> +
> +	if (pmic_write(dev->parent, PCA9450_SW_RST, &cmd, 1)) {
> +		dev_err(dev, "reset command failed\n");
> +	} else {
> +		/* tRESTART is 250ms, delay 300ms just to be sure */
> +		mdelay(300);
> +		/* Should not get here, warn if we do */
> +		dev_warn(dev, "didn't respond to reset command\n");
> +	}
> +
> +	return -EINPROGRESS;
> +}
> +
> +static struct sysreset_ops pca9450_sysreset_ops = {
> +	.request	= pca9450_sysreset_request,

When using the PCA9450 to perform a cold reset, the CPU boot status shall
_always_ be POR, as that is what the CPU detects. This means the boot status
should also come from the PCA9450 when enabling CONFIG_SYSRESET option.

I think implementing pca9450_sysreset_ops.get_status() to read the
PWRON_STAT register should do the trick, but I am not that familiar with the
sysreset in U-Boot.

> +};
> +
> +U_BOOT_DRIVER(pca9450_sysreset) = {
> +	.name		= "pca9450_sysreset",
> +	.id		= UCLASS_SYSRESET,
> +	.ops		= &pca9450_sysreset_ops,
> +};
> +#endif /* CONFIG_SYSRESET */
> diff --git a/include/power/pca9450.h b/include/power/pca9450.h
> index e5ab09fb8c83..9119ef793b1f 100644
> --- a/include/power/pca9450.h
> +++ b/include/power/pca9450.h
> @@ -75,4 +75,6 @@ enum {
>  #define PCA9450_PMIC_RESET_WDOG_B_CFG_WARM		0x40
>  #define PCA9450_PMIC_RESET_WDOG_B_CFG_COLD_LDO12	0x80
>  
> +#define PCA9450_SW_RST_COLD_RST		0x14
> +
>  #endif
> 

Thanks for porting it to U-Boot :-)

br,
Paul