mirror of https://github.com/torvalds/linux.git
62 lines
1.8 KiB
C
62 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* am33xx-restart.c - Code common to all AM33xx machines.
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*/
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#include <dt-bindings/pinctrl/am33xx.h>
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#include <linux/delay.h>
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#include <linux/kernel.h>
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#include <linux/reboot.h>
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#include "common.h"
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#include "control.h"
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#include "prm.h"
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/*
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* Advisory 1.0.36 EMU0 and EMU1: Terminals Must be Pulled High Before
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* ICEPick Samples
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*
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* If EMU0/EMU1 pins have been used as GPIO outputs and actively driving low
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* level, the device might not reboot in normal mode. We are in a bad position
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* to override GPIO state here, so just switch the pins into EMU input mode
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* (that's what reset will do anyway) and wait a bit, because the state will be
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* latched 190 ns after reset.
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*/
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static void am33xx_advisory_1_0_36(void)
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{
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u32 emu0 = omap_ctrl_readl(AM335X_PIN_EMU0);
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u32 emu1 = omap_ctrl_readl(AM335X_PIN_EMU1);
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/* If both pins are in EMU mode, nothing to do */
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if (!(emu0 & 7) && !(emu1 & 7))
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return;
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/* Switch GPIO3_7/GPIO3_8 into EMU0/EMU1 modes respectively */
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omap_ctrl_writel(emu0 & ~7, AM335X_PIN_EMU0);
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omap_ctrl_writel(emu1 & ~7, AM335X_PIN_EMU1);
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/*
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* Give pull-ups time to load the pin/PCB trace capacity.
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* 5 ms shall be enough to load 1 uF (would be huge capacity for these
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* pins) with TI-recommended 4k7 external pull-ups.
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*/
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mdelay(5);
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}
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/**
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* am33xx_restart - trigger a software restart of the SoC
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* @mode: the "reboot mode", see arch/arm/kernel/{setup,process}.c
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* @cmd: passed from the userspace program rebooting the system (if provided)
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*
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* Resets the SoC. For @cmd, see the 'reboot' syscall in
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* kernel/sys.c. No return value.
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*/
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void am33xx_restart(enum reboot_mode mode, const char *cmd)
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{
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am33xx_advisory_1_0_36();
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/* TODO: Handle cmd if necessary */
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prm_reboot_mode = mode;
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omap_prm_reset_system();
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}
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