Subject: [PATCH 05/18] power: reset: Add AT91 reset driver

From: [email-masked] (Maxime Ripard)
Date: Thu, 3 Jul 2014 16:59:57 +0200

On Thu, Jul 03, 2014 at 10:39:08PM +0800, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > +++ b/drivers/power/reset/at91-reset.c
> > @@ -0,0 +1,202 @@
> > +/*
> > + * Atmel AT91 SAM9 SoCs reset code
> > + *
> > + * Copyright (C) 2014 Maxime Ripard
> > + *
> > + * Maxime Ripard <[email-masked]>
> 
> you can not own the copyright as it?s basically a copy of other
> people code

The previous names are missing, right.

> > + *
> > + * This file is licensed under the terms of the GNU General Public
> > + * License version 2.  This program is licensed "as is" without any
> > + * warranty of any kind, whether express or implied.
> > + */
> > +
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/reboot.h>
> > +
> > +#include <asm/system_misc.h>
> > +
> > +#include <mach/at91sam9_ddrsdr.h>
> > +#include <mach/at91sam9_sdramc.h>
> > +
> > +#define AT91_RSTC_CR	0x00		/* Reset Controller Control Register */
> > +#define	AT91_RSTC_PROCRST	BIT(0)		/* Processor Reset */
> > +#define	AT91_RSTC_PERRST	BIT(2)		/* Peripheral Reset */
> > +#define	AT91_RSTC_EXTRST	BIT(3)		/* External Reset */
> > +#define	AT91_RSTC_KEY		(0xa5 << 24)	/* KEY Password */
> > +
> > +#define AT91_RSTC_SR	0x04		/* Reset Controller Status Register */
> > +#define	AT91_RSTC_URSTS		BIT(0)		/* User Reset Status */
> > +#define	AT91_RSTC_RSTTYP	GENMASK(10, 8)	/* Reset Type */
> > +#define	AT91_RSTC_NRSTL		BIT(16)		/* NRST Pin Level */
> > +#define	AT91_RSTC_SRCMP		BIT(17)		/* Software Reset Command in Progress */
> > +
> > +#define AT91_RSTC_MR	0x08		/* Reset Controller Mode Register */
> > +#define	AT91_RSTC_URSTEN	BIT(0)		/* User Reset Enable */
> > +#define	AT91_RSTC_URSTIEN	BIT(4)		/* User Reset Interrupt Enable */
> > +#define	AT91_RSTC_ERSTL		GENMASK(11, 8)	/* External Reset Length */
> > +
> > +enum reset_type {
> > +	RESET_TYPE_GENERAL	= 0,
> > +	RESET_TYPE_WAKEUP	= 1,
> > +	RESET_TYPE_WATCHDOG	= 2,
> > +	RESET_TYPE_SOFTWARE	= 3,
> > +	RESET_TYPE_USER		= 4,
> > +};
> > +
> > +static void __iomem *at91_ramc_base[2], *at91_rstc_base;
> > +
> > +static void at91sam9_restart(enum reboot_mode mode, const char *cmd)
> > +{
> > +	asm volatile(
> > +		".balign 32\n\t"
> > +
> > +		"str	%2, [%0, #" __stringify(AT91_SDRAMC_TR) "]\n\t"
> > +		"str	%3, [%0, #" __stringify(AT91_SDRAMC_LPR) "]\n\t"
> > +		"str	%4, [%1, #" __stringify(AT91_RSTC_CR) "]\n\t"
> > +
> > +		"b	.\n\t"
> > +		:
> > +		: "r" (at91_ramc_base[0]),
> > +		  "r" (at91_rstc_base),
> > +		  "r" (1),
> > +		  "r" (AT91_SDRAMC_LPCB_POWER_DOWN),
> > +		  "r" (AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST));
> > +}
> > +
> > +static void at91sam9g45_restart(enum reboot_mode mode, const char *cmd)
> > +{
> > +	asm volatile(
> > +		"cmp	%1, #0\n\t"
> > +		"beq	1f\n\t"
> > +
> > +		"ldr	r0, [%1]\n\t"
> > +		"cmp	r0, #0\n\t"
> > +
> > +		".balign 32\n\t"
> > +
> > +		"1:	str	%3, [%0, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
> > +		"	str	%4, [%0, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
> > +		"	strne	%3, [%1, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
> > +		"	strne	%4, [%1, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
> > +		"	str	%5, [%2, #" __stringify(AT91_RSTC_CR) "]\n\t"
> > +
> > +		"	b	.\n\t"
> > +		:
> > +		: "r" (at91_ramc_base[0]),
> > +		  "r" (at91_ramc_base[1]),
> > +		  "r" (at91_rstc_base),
> > +		  "r" (1),
> > +		  "r" (AT91_DDRSDRC_LPCB_POWER_DOWN),
> > +		  "r" (AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST)
> > +		: "r0");
> > +}
> > +
> move this to an assembly file more easy to read than a C code

Nope. It's a pain to pass variable to an external assembly file, and
this makes the use of global variable pretty much mandatory, which is
definitely not great.

> 
> > +static void __init at91_reset_status(struct platform_device *pdev)
> > +{
> > +	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
> > +	char *reason;
> > +
> > +	switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
> > +	case RESET_TYPE_GENERAL:
> > +		reason = "general reset";
> > +		break;
> > +	case RESET_TYPE_WAKEUP:
> > +		reason = "wakeup";
> > +		break;
> > +	case RESET_TYPE_WATCHDOG:
> > +		reason = "watchdog reset";
> > +		break;
> > +	case RESET_TYPE_SOFTWARE:
> > +		reason = "software reset";
> > +		break;
> > +	case RESET_TYPE_USER:
> > +		reason = "user reset";
> > +		break;
> > +	default:
> > +		reason = "unknown reset";
> > +		break;
> > +	}
> > +
> > +	pr_info("AT91: Starting after %s\n", reason);
> > +}
> > +
> > +static struct of_device_id at91_ramc_of_match[] = {
> > +	{ .compatible = "atmel,at91sam9260-sdramc", },
> > +	{ .compatible = "atmel,at91sam9g45-ddramc", },
> > +	{ /* sentinel */ }
> > +};
> > +
> > +static struct of_device_id at91_reset_of_match[] = {
> > +	{ .compatible = "atmel,at91sam9260-rstc", .data = at91sam9_restart },
> > +	{ .compatible = "atmel,at91sam9g45-rstc", .data = at91sam9g45_restart },
> > +	{ /* sentinel */ }
> > +};
> > +
> > +static int at91_reset_probe(struct platform_device *pdev)
> > +{
> > +	struct resource *res;
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	at91_rstc_base = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(at91_rstc_base)) {
> > +		dev_err(&pdev->dev, "Could not map reset controller address\n");
> > +		return PTR_ERR(at91_rstc_base);
> > +	}
> > +
> > +	if (pdev->dev.of_node) {
> 
> split in 2 function more easy to ready and less indentation

ok.

> > +		const struct of_device_id *match;
> > +		struct device_node *np;
> > +		int idx = 0;
> > +
> > +		for_each_matching_node(np, at91_ramc_of_match) {
> > +			at91_ramc_base[idx] = of_iomap(np, 0);
> > +			if (!at91_ramc_base[idx]) {
> > +				dev_err(&pdev->dev, "Could not map ram controller address\n");
> > +				return -ENODEV;
> > +			}
> > +			idx++;
> > +		}
> 
> and if you can not probe the ram controler it?s a panic not a -ENODEV
> 
> as you have an unstable platform

I don't really see why. That the pm code and the reset code won't be
able to work, it's obvious. But making the assumption that the
platforms don't have a RAM properly setup just because it doesn't have
a DT node seems quite weak.

> > +
> > +		match = of_match_node(at91_reset_of_match, pdev->dev.of_node);
> > +		arm_pm_restart = match->data;
> > +	} else {
> > +		const struct platform_device_id *match;
> > +		int idx = 0;
> > +
> > +		for (idx = 0; idx < 2; idx++) {
> > +			res = platform_get_resource(pdev, IORESOURCE_MEM, idx + 1 );
> > +			at91_ramc_base[idx] = devm_ioremap_resource(&pdev->dev, res);
> > +			if (IS_ERR(at91_ramc_base[idx])) {
> > +				dev_err(&pdev->dev, "Could not map ram controller address\n");
> > +				return PTR_ERR(at91_rstc_base);
> > +			}
> > +		}
> > +
> > +		match = platform_get_device_id(pdev);
> > +		arm_pm_restart = (void (*)(enum reboot_mode, const char*))
> > +			match->driver_data;
> > +	}
> > +
> > +	at91_reset_status(pdev);
> > +
> > +	return 0;
> > +}
> > +
> > +static struct platform_device_id at91_reset_plat_match[] = {
> > +	{ "at91-sam9-reset", (unsigned long)at91sam9_restart },
> > +	{ "at91-g45-reset", (unsigned long)at91sam9g45_restart },
> 	    at91-sam9???
> 
> 	    from the beginning of DT we put the first SoC were the
> 	    reset was introduce and why do you change the DT binding?

Except that this is not about DT probing, but the old-style board
files one.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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