forked from Minki/linux
2b2c6148fe
Commit dca1a4b5ff ("clk: at91: keep slow clk enabled to prevent system
hang") added a workaround for the slow clock as it is not properly handled
by its users.
Get and use the slow clock as it is necessary for the at91 reset
controller.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
258 lines
6.8 KiB
C
258 lines
6.8 KiB
C
/*
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* Atmel AT91 SAM9 SoCs reset code
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*
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* Copyright (C) 2007 Atmel Corporation.
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* Copyright (C) BitBox Ltd 2010
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* Copyright (C) 2011 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcosoft.com>
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* Copyright (C) 2014 Free Electrons
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/of_address.h>
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#include <linux/platform_device.h>
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#include <linux/reboot.h>
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#include <soc/at91/at91sam9_ddrsdr.h>
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#include <soc/at91/at91sam9_sdramc.h>
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#define AT91_RSTC_CR 0x00 /* Reset Controller Control Register */
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#define AT91_RSTC_PROCRST BIT(0) /* Processor Reset */
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#define AT91_RSTC_PERRST BIT(2) /* Peripheral Reset */
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#define AT91_RSTC_EXTRST BIT(3) /* External Reset */
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#define AT91_RSTC_KEY (0xa5 << 24) /* KEY Password */
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#define AT91_RSTC_SR 0x04 /* Reset Controller Status Register */
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#define AT91_RSTC_URSTS BIT(0) /* User Reset Status */
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#define AT91_RSTC_RSTTYP GENMASK(10, 8) /* Reset Type */
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#define AT91_RSTC_NRSTL BIT(16) /* NRST Pin Level */
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#define AT91_RSTC_SRCMP BIT(17) /* Software Reset Command in Progress */
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#define AT91_RSTC_MR 0x08 /* Reset Controller Mode Register */
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#define AT91_RSTC_URSTEN BIT(0) /* User Reset Enable */
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#define AT91_RSTC_URSTIEN BIT(4) /* User Reset Interrupt Enable */
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#define AT91_RSTC_ERSTL GENMASK(11, 8) /* External Reset Length */
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enum reset_type {
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RESET_TYPE_GENERAL = 0,
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RESET_TYPE_WAKEUP = 1,
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RESET_TYPE_WATCHDOG = 2,
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RESET_TYPE_SOFTWARE = 3,
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RESET_TYPE_USER = 4,
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};
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static void __iomem *at91_ramc_base[2], *at91_rstc_base;
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static struct clk *sclk;
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/*
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* unless the SDRAM is cleanly shutdown before we hit the
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* reset register it can be left driving the data bus and
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* killing the chance of a subsequent boot from NAND
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*/
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static int at91sam9260_restart(struct notifier_block *this, unsigned long mode,
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void *cmd)
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{
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asm volatile(
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/* Align to cache lines */
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".balign 32\n\t"
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/* Disable SDRAM accesses */
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"str %2, [%0, #" __stringify(AT91_SDRAMC_TR) "]\n\t"
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/* Power down SDRAM */
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"str %3, [%0, #" __stringify(AT91_SDRAMC_LPR) "]\n\t"
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/* Reset CPU */
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"str %4, [%1, #" __stringify(AT91_RSTC_CR) "]\n\t"
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"b .\n\t"
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:
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: "r" (at91_ramc_base[0]),
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"r" (at91_rstc_base),
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"r" (1),
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"r" cpu_to_le32(AT91_SDRAMC_LPCB_POWER_DOWN),
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"r" cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST));
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return NOTIFY_DONE;
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}
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static int at91sam9g45_restart(struct notifier_block *this, unsigned long mode,
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void *cmd)
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{
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asm volatile(
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/*
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* Test wether we have a second RAM controller to care
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* about.
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*
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* First, test that we can dereference the virtual address.
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*/
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"cmp %1, #0\n\t"
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"beq 1f\n\t"
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/* Then, test that the RAM controller is enabled */
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"ldr r0, [%1]\n\t"
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"cmp r0, #0\n\t"
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/* Align to cache lines */
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".balign 32\n\t"
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/* Disable SDRAM0 accesses */
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"1: str %3, [%0, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
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/* Power down SDRAM0 */
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" str %4, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
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/* Disable SDRAM1 accesses */
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" strne %3, [%1, #" __stringify(AT91_DDRSDRC_RTR) "]\n\t"
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/* Power down SDRAM1 */
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" strne %4, [%1, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
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/* Reset CPU */
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" str %5, [%2, #" __stringify(AT91_RSTC_CR) "]\n\t"
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" b .\n\t"
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:
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: "r" (at91_ramc_base[0]),
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"r" (at91_ramc_base[1]),
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"r" (at91_rstc_base),
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"r" (1),
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"r" cpu_to_le32(AT91_DDRSDRC_LPCB_POWER_DOWN),
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"r" cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST)
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: "r0");
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return NOTIFY_DONE;
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}
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static int sama5d3_restart(struct notifier_block *this, unsigned long mode,
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void *cmd)
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{
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writel(cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST),
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at91_rstc_base);
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return NOTIFY_DONE;
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}
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static void __init at91_reset_status(struct platform_device *pdev)
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{
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u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
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char *reason;
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switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
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case RESET_TYPE_GENERAL:
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reason = "general reset";
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break;
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case RESET_TYPE_WAKEUP:
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reason = "wakeup";
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break;
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case RESET_TYPE_WATCHDOG:
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reason = "watchdog reset";
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break;
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case RESET_TYPE_SOFTWARE:
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reason = "software reset";
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break;
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case RESET_TYPE_USER:
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reason = "user reset";
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break;
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default:
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reason = "unknown reset";
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break;
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}
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pr_info("AT91: Starting after %s\n", reason);
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}
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static const struct of_device_id at91_ramc_of_match[] = {
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{ .compatible = "atmel,at91sam9260-sdramc", },
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{ .compatible = "atmel,at91sam9g45-ddramc", },
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{ /* sentinel */ }
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};
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static const struct of_device_id at91_reset_of_match[] = {
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{ .compatible = "atmel,at91sam9260-rstc", .data = at91sam9260_restart },
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{ .compatible = "atmel,at91sam9g45-rstc", .data = at91sam9g45_restart },
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{ .compatible = "atmel,sama5d3-rstc", .data = sama5d3_restart },
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{ /* sentinel */ }
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};
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static struct notifier_block at91_restart_nb = {
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.priority = 192,
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};
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static int __init at91_reset_probe(struct platform_device *pdev)
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{
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const struct of_device_id *match;
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struct device_node *np;
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int ret, idx = 0;
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at91_rstc_base = of_iomap(pdev->dev.of_node, 0);
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if (!at91_rstc_base) {
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dev_err(&pdev->dev, "Could not map reset controller address\n");
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return -ENODEV;
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}
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if (!of_device_is_compatible(pdev->dev.of_node, "atmel,sama5d3-rstc")) {
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/* we need to shutdown the ddr controller, so get ramc base */
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for_each_matching_node(np, at91_ramc_of_match) {
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at91_ramc_base[idx] = of_iomap(np, 0);
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if (!at91_ramc_base[idx]) {
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dev_err(&pdev->dev, "Could not map ram controller address\n");
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return -ENODEV;
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}
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idx++;
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}
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}
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match = of_match_node(at91_reset_of_match, pdev->dev.of_node);
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at91_restart_nb.notifier_call = match->data;
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sclk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(sclk))
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return PTR_ERR(sclk);
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ret = clk_prepare_enable(sclk);
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if (ret) {
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dev_err(&pdev->dev, "Could not enable slow clock\n");
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return ret;
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}
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ret = register_restart_handler(&at91_restart_nb);
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if (ret) {
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clk_disable_unprepare(sclk);
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return ret;
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}
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at91_reset_status(pdev);
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return 0;
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}
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static int __exit at91_reset_remove(struct platform_device *pdev)
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{
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unregister_restart_handler(&at91_restart_nb);
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clk_disable_unprepare(sclk);
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return 0;
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}
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static const struct platform_device_id at91_reset_plat_match[] = {
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{ "at91-sam9260-reset", (unsigned long)at91sam9260_restart },
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{ "at91-sam9g45-reset", (unsigned long)at91sam9g45_restart },
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{ /* sentinel */ }
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};
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static struct platform_driver at91_reset_driver = {
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.remove = __exit_p(at91_reset_remove),
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.driver = {
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.name = "at91-reset",
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.of_match_table = at91_reset_of_match,
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},
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.id_table = at91_reset_plat_match,
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};
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module_platform_driver_probe(at91_reset_driver, at91_reset_probe);
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MODULE_AUTHOR("Atmel Corporation");
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MODULE_DESCRIPTION("Reset driver for Atmel SoCs");
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MODULE_LICENSE("GPL v2");
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