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SubjectRe: [PATCH 05/18] power: reset: Add AT91 reset driver
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On Jul 3, 2014, at 10:59 PM, Maxime Ripard <maxime.ripard@free-electrons.com> wrote:

> 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 <maxime.ripard@free-electrons.com>
>>
>> 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.

Not at all I did for the PM slow clock code just write a function and pas it as a parameter
you have 3

so basically you have to use the current and just pass at91_ramc_base[0], at91_ramc_base[1]
and at91_rstc_base
it’s 3 lignes of modification, if you have at91_ramc_base and at91_ramc_base same

so NACK
>
>>
>>> +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.

no as if you do not have the RAMC your reset will cause hardware issue as there is a bug
in the SoC so yes mandatory as 95% of the people will not known why there board will suddenly
do not reboot. As this specific reset in assembly was write to run from cache to fix a SoC bug
in the reset controller
>
>>> +
>>> + 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.
>

except that in al the other driver such as FBDEV we use the same principle for platform_device

Best Regards,
J.

> Maxime
>
> --
> Maxime Ripard, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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