diff options
Diffstat (limited to 'arch/arm/mach-omap2/am33xx-restart.c')
| -rw-r--r-- | arch/arm/mach-omap2/am33xx-restart.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/arm/mach-omap2/am33xx-restart.c b/arch/arm/mach-omap2/am33xx-restart.c index fcf3d557aa78..3cdf223addcc 100644 --- a/arch/arm/mach-omap2/am33xx-restart.c +++ b/arch/arm/mach-omap2/am33xx-restart.c @@ -2,12 +2,46 @@ /* * am33xx-restart.c - Code common to all AM33xx machines. */ +#include <dt-bindings/pinctrl/am33xx.h> +#include <linux/delay.h> #include <linux/kernel.h> #include <linux/reboot.h> #include "common.h" +#include "control.h" #include "prm.h" +/* + * Advisory 1.0.36 EMU0 and EMU1: Terminals Must be Pulled High Before + * ICEPick Samples + * + * If EMU0/EMU1 pins have been used as GPIO outputs and actively driving low + * level, the device might not reboot in normal mode. We are in a bad position + * to override GPIO state here, so just switch the pins into EMU input mode + * (that's what reset will do anyway) and wait a bit, because the state will be + * latched 190 ns after reset. + */ +static void am33xx_advisory_1_0_36(void) +{ + u32 emu0 = omap_ctrl_readl(AM335X_PIN_EMU0); + u32 emu1 = omap_ctrl_readl(AM335X_PIN_EMU1); + + /* If both pins are in EMU mode, nothing to do */ + if (!(emu0 & 7) && !(emu1 & 7)) + return; + + /* Switch GPIO3_7/GPIO3_8 into EMU0/EMU1 modes respectively */ + omap_ctrl_writel(emu0 & ~7, AM335X_PIN_EMU0); + omap_ctrl_writel(emu1 & ~7, AM335X_PIN_EMU1); + + /* + * Give pull-ups time to load the pin/PCB trace capacity. + * 5 ms shall be enough to load 1 uF (would be huge capacity for these + * pins) with TI-recommended 4k7 external pull-ups. + */ + mdelay(5); +} + /** * am33xx_restart - trigger a software restart of the SoC * @mode: the "reboot mode", see arch/arm/kernel/{setup,process}.c @@ -18,6 +52,8 @@ */ void am33xx_restart(enum reboot_mode mode, const char *cmd) { + am33xx_advisory_1_0_36(); + /* TODO: Handle cmd if necessary */ prm_reboot_mode = mode; |