Re: [PATCH v3] ARM: rpi: parse useful data from vc fdt

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Daniel,

On 15.06.22 20:41, Daniel Brát wrote:
> Videocore first-stage loader on rpi passes us many useful information
> inside the vc fdt, including the real value of PM_RSTS register, not
> easily available by other means and which we can use to determine
> the reset cause.
> Also make the relevant funtions just print error/warning and continue
> in case of some errors, since the fdt from vc is now optional for
> barebox's basic function.
> 
> Signed-off-by: Daniel Brát <danek.brat@gmail.com>
> ---
>  arch/arm/boards/raspberry-pi/rpi-common.c | 167 ++++++++++++++++------
>  drivers/watchdog/bcm2835_wdt.c            |  23 +--
>  include/soc/bcm283x/wdt.h                 |  40 ++++++
>  3 files changed, 167 insertions(+), 63 deletions(-)
>  create mode 100644 include/soc/bcm283x/wdt.h
> 
> diff --git a/arch/arm/boards/raspberry-pi/rpi-common.c b/arch/arm/boards/raspberry-pi/rpi-common.c
> index 12a4f4a0a..308a7085c 100644
> --- a/arch/arm/boards/raspberry-pi/rpi-common.c
> +++ b/arch/arm/boards/raspberry-pi/rpi-common.c
> @@ -23,13 +23,28 @@
>  #include <linux/sizes.h>
>  #include <globalvar.h>
>  #include <asm/system_info.h>
> +#include <reset_source.h>
>  
>  #include <mach/core.h>
>  #include <mach/mbox.h>
>  #include <mach/platform.h>
>  
> +#include <soc/bcm283x/wdt.h>
> +
>  #include "lowlevel.h"
>  
> +//https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#BOOT_ORDER
> +static const char * const boot_mode_names[] = {
> +	[0x0] = "unknown",
> +	[0x1] = "sd",
> +	[0x2] = "net",
> +	[0x3] = "rpiboot",
> +	[0x4] = "usbmsd",
> +	[0x5] = "usbc",
> +	[0x6] = "nvme",
> +	[0x7] = "http",
> +};
> +
>  struct rpi_priv;
>  struct rpi_machine_data {
>  	int (*init)(struct rpi_priv *priv);
> @@ -186,54 +201,117 @@ static int rpi_env_init(void)
>  	return 0;
>  }
>  
> -/* Extract /chosen/bootargs from the VideoCore FDT into vc.bootargs
> - * global variable. */
> -static int rpi_vc_fdt_bootargs(void *fdt)
> +/* Extract useful information from the VideoCore FDT we got.
> + * Some parameters are defined here:
> + * https://www.raspberrypi.com/documentation/computers/configuration.html#part4
> + */
> +static void rpi_vc_fdt_parse(void *fdt)
>  {
> -	int ret = 0;
> -	struct device_node *root = NULL, *node;
> -	const char *cmdline;
> +	int ret, len;
> +	struct device_node *root, *chosen, *bootloader;
> +	enum reset_src_type rst_src = RESET_UKWN;
> +	const char *str;
> +	char *dynstr;
> +	u32 num, *pnum;
>  
>  	root = of_unflatten_dtb(fdt, INT_MAX);
> -	if (IS_ERR(root)) {
> -		ret = PTR_ERR(root);
> -		root = NULL;
> -		goto out;
> +	if (IS_ERR(root))
> +		return;
> +
> +	str = of_get_property(root, "serial-number", &len);
> +	if (!str) {
> +		pr_warn("no 'serial-number' property found in vc fdt\n");
> +	} else {
> +		dynstr = xstrndup(str, len);
> +		barebox_set_serial_number(dynstr);
> +		free(dynstr);
>  	}

How about:

static const char *of_read_vc_string(struct device_node *root,
                                     const char *propname)
{
        const char *str;
        char *dynstr;
        int len;

        str = of_get_property(root, propname, &len);
        if (!str) {
                pr_warn("no '%s' property found in vc fdt\n", propname);
                return NULL;
        };

        return xstrndup(str, len);
}

and then use it throughout?

This should make the code much better readable IMO.

>  
> -	node = of_find_node_by_path_from(root, "/chosen");
> -	if (!node) {
> -		pr_err("no /chosen node\n");
> -		ret = -ENOENT;
> -		goto out;
> +	str = of_get_property(root, "model", &len);
> +	if (!str) {
> +		pr_warn("no 'model' property found in vc fdt\n");
> +	} else {
> +		dynstr = xstrndup(str, len);
> +		barebox_set_model(dynstr);
> +		free(dynstr);
>  	}
>  
> -	cmdline = of_get_property(node, "bootargs", NULL);
> -	if (!cmdline) {
> -		pr_err("no bootargs property in the /chosen node\n");
> -		ret = -ENOENT;
> +	chosen = of_find_node_by_path_from(root, "/chosen");
> +	if (!chosen) {
> +		pr_err("no '/chosen' node found in vc fdt\n");
>  		goto out;
>  	}
>  
> -	globalvar_add_simple("vc.bootargs", cmdline);
> +	bootloader = of_find_node_by_name(chosen, "bootloader");
> +
> +	str = of_get_property(chosen, "bootargs", &len);
> +	if (!str)
> +		pr_warn("no 'bootargs' property in the /chosen node\n");
> +	else
> +		globalvar_add_simple("vc.bootargs", xstrndup(str, len));

second argument is xstrdup'd, so this leaks.

> +
> +	str = of_get_property(chosen, "overlay_prefix", &len);
> +	if (!str)
> +		pr_warn("no 'overlay_prefix' property in the /chosen node\n");
> +	else
> +		globalvar_add_simple("vc.overlay_prefix", xstrndup(str, len));
> +
> +	str = of_get_property(chosen, "os_prefix", &len);
> +	if (!str)
> +		pr_warn("no 'os_prefix' property in the /chosen node\n");
> +	else
> +		globalvar_add_simple("vc.os_prefix", xstrndup(str, len));
> +
> +	ret = of_property_read_u32(chosen, "boot-mode", &num);
> +	if (ret && bootloader)
> +		ret = of_property_read_u32(bootloader, "boot-mode", &num);
> +	if (ret) {
> +		pr_warn("'boot-mode' property not found\n");

Nitpick: Did they always populate this property? I would skip this warning here, so
it doesn't spam old firmware + new barebox.

> +	} else {
> +		pnum = xmalloc(sizeof(u32));

Just make it a static variable?

> +		*pnum = num;
> +		globalvar_add_simple_enum("vc.boot_mode", pnum,
> +					  boot_mode_names,
> +					  ARRAY_SIZE(boot_mode_names));
> +	}
>  
> -	switch(cpu_architecture()) {
> -	case CPU_ARCH_ARMv6:
> -		globalvar_add_simple("vc.kernel", "kernel.img");
> -		break;
> -	case CPU_ARCH_ARMv7:
> -		globalvar_add_simple("vc.kernel", "kernel7.img");
> -		break;
> -	case CPU_ARCH_ARMv8:
> -		globalvar_add_simple("vc.kernel", "kernel8.img");
> -		break;
> +	ret = of_property_read_u32(chosen, "partition", &num);
> +	if (ret && bootloader)
> +		ret = of_property_read_u32(bootloader, "partition", &num);
> +	if (ret) {
> +		pr_warn("'partition' property not found\n");
> +	} else {
> +		pnum = xmalloc(sizeof(u32));
> +		*pnum = num;
> +		globalvar_add_simple_int("vc.boot_partition", pnum, "%u");
>  	}
>  
> +	if (IS_ENABLED(CONFIG_RESET_SOURCE)) {
> +		ret = of_property_read_u32(chosen, "pm_rsts", &num);
> +		if (ret && bootloader)
> +			 ret = of_property_read_u32(bootloader, "rsts", &num);
> +
> +		if (ret) {
> +			pr_warn("'pm_rsts'/'rsts' property not found\n");
> +		} else {
> +/*
> + * https://github.com/raspberrypi/linux/issues/932#issuecomment-93989581
> + */
> +			if (num & PM_RSTS_HADPOR_SET)
> +				rst_src = RESET_POR;
> +			else if (num & PM_RSTS_HADDR_SET)
> +				rst_src = RESET_JTAG;
> +			else if (num & PM_RSTS_HADWR_SET)
> +				rst_src = RESET_WDG;
> +			else if (num & PM_RSTS_HADSR_SET)
> +				rst_src = RESET_RST;
> +			reset_source_set(rst_src);
> +		}
> +	}
>  out:
>  	if (root)
>  		of_delete_node(root);
> -
> -	return ret;
> +	return;
>  }
>  
>  static void rpi_vc_fdt(void)
> @@ -241,7 +319,6 @@ static void rpi_vc_fdt(void)
>  	void *saved_vc_fdt;
>  	struct fdt_header *oftree;
>  	unsigned long magic, size;
> -	int ret;
>  
>  	/* VideoCore FDT was copied in PBL just above Barebox memory */
>  	saved_vc_fdt = (void *)(arm_mem_endmem_get());
> @@ -260,16 +337,23 @@ static void rpi_vc_fdt(void)
>  		return;
>  
>  	size = be32_to_cpu(oftree->totalsize);
> -	if (write_file("/vc.dtb", saved_vc_fdt, size)) {
> +	if (write_file("/vc.dtb", saved_vc_fdt, size))
>  		pr_err("failed to save videocore fdt to a file\n");
> -		return;
> -	}
>  
> -	ret = rpi_vc_fdt_bootargs(saved_vc_fdt);
> -	if (ret) {
> -		pr_err("failed to extract bootargs from videocore fdt: %d\n",
> -									ret);
> -		return;
> +	rpi_vc_fdt_parse(saved_vc_fdt);
> +}
> +
> +static void rpi_set_kernel_name(void) {
> +	switch(cpu_architecture()) {
> +	case CPU_ARCH_ARMv6:
> +		globalvar_add_simple("vc.kernel", "kernel.img");
> +		break;
> +	case CPU_ARCH_ARMv7:
> +		globalvar_add_simple("vc.kernel", "kernel7.img");
> +		break;
> +	case CPU_ARCH_ARMv8:
> +		globalvar_add_simple("vc.kernel", "kernel8.img");
> +		break;
>  	}
>  }
>  
> @@ -348,6 +432,7 @@ static int rpi_devices_probe(struct device_d *dev)
>  	armlinux_set_architecture(MACH_TYPE_BCM2708);
>  	rpi_env_init();
>  	rpi_vc_fdt();
> +	rpi_set_kernel_name();
>  
>  	if (dcfg && dcfg->init)
>  		dcfg->init(priv);
> diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
> index ece80837b..c6e6a289f 100644
> --- a/drivers/watchdog/bcm2835_wdt.c
> +++ b/drivers/watchdog/bcm2835_wdt.c
> @@ -10,28 +10,7 @@
>  #include <restart.h>
>  #include <watchdog.h>
>  
> -#define PM_RSTC		0x1c
> -#define PM_RSTS		0x20
> -#define PM_WDOG		0x24
> -
> -#define PM_WDOG_RESET				0000000000
> -#define PM_PASSWORD				0x5a000000
> -#define PM_WDOG_TIME_SET			0x000fffff
> -#define PM_RSTC_WRCFG_CLR			0xffffffcf
> -#define PM_RSTC_WRCFG_SET			0x00000030
> -#define PM_RSTC_WRCFG_FULL_RESET		0x00000020
> -#define PM_RSTC_RESET				0x00000102
> -
> -#define PM_RSTS_HADPOR_SET			0x00001000
> -#define PM_RSTS_HADSRH_SET			0x00000400
> -#define PM_RSTS_HADSRF_SET			0x00000200
> -#define PM_RSTS_HADSRQ_SET			0x00000100
> -#define PM_RSTS_HADWRH_SET			0x00000040
> -#define PM_RSTS_HADWRF_SET			0x00000020
> -#define PM_RSTS_HADWRQ_SET			0x00000010
> -#define PM_RSTS_HADDRH_SET			0x00000004
> -#define PM_RSTS_HADDRF_SET			0x00000002
> -#define PM_RSTS_HADDRQ_SET			0x00000001
> +#include <soc/bcm283x/wdt.h>
>  
>  #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
>  
> diff --git a/include/soc/bcm283x/wdt.h b/include/soc/bcm283x/wdt.h
> new file mode 100644
> index 000000000..ce97b1eb5
> --- /dev/null
> +++ b/include/soc/bcm283x/wdt.h
> @@ -0,0 +1,40 @@
> +/*
> + * Copyright (C) 2017 Pengutronix, Lucas Stach <l.stach@pengutronix.de>
> + *
> + * Based on code from  Carlo Caione <carlo@carlocaione.org>
> + */
> +
> +#ifndef __BCM2835_WDT_H
> +#define __BCM2835_WDT_H
> +
> +#define PM_RSTC				0x1c
> +#define PM_RSTS				0x20
> +#define PM_WDOG				0x24
> +
> +#define PM_WDOG_RESET			0000000000
> +#define PM_PASSWORD			0x5a000000
> +#define PM_WDOG_TIME_SET		0x000fffff
> +#define PM_RSTC_WRCFG_CLR		0xffffffcf
> +#define PM_RSTC_WRCFG_SET		0x00000030
> +#define PM_RSTC_WRCFG_FULL_RESET	0x00000020
> +#define PM_RSTC_RESET			0x00000102
> +
> +#define PM_RSTS_HADPOR_SET		0x00001000
> +#define PM_RSTS_HADSRH_SET		0x00000400
> +#define PM_RSTS_HADSRF_SET		0x00000200
> +#define PM_RSTS_HADSRQ_SET		0x00000100
> +#define PM_RSTS_HADWRH_SET		0x00000040
> +#define PM_RSTS_HADWRF_SET		0x00000020
> +#define PM_RSTS_HADWRQ_SET		0x00000010
> +#define PM_RSTS_HADDRH_SET		0x00000004
> +#define PM_RSTS_HADDRF_SET		0x00000002
> +#define PM_RSTS_HADDRQ_SET		0x00000001
> +
> +#define PM_RSTS_HADDR_SET \
> +	(PM_RSTS_HADDRQ_SET | PM_RSTS_HADDRF_SET | PM_RSTS_HADDRH_SET)
> +#define PM_RSTS_HADWR_SET \
> +	(PM_RSTS_HADWRQ_SET | PM_RSTS_HADWRF_SET | PM_RSTS_HADWRH_SET)
> +#define PM_RSTS_HADSR_SET \
> +	(PM_RSTS_HADSRQ_SET | PM_RSTS_HADSRF_SET | PM_RSTS_HADSRH_SET)
> +
> +#endif


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