From 92335a0d4021a3b44ccc88c9fc6c0fd2113f1882 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Sun, 29 Jun 2014 18:38:39 +0100 Subject: [PATCH] hw/arm/strongarm: Fix handling of GPSR/GPCR reads The StrongARM GPIO GPSR and GPCR registers are write-only, with reads being undefined behaviour. Instead of having GPCR return 31337 and GPSR return the value last written, make both log the guest error and return 0. Signed-off-by: Peter Maydell Reviewed-by: Peter Crosthwaite --- hw/arm/strongarm.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/hw/arm/strongarm.c b/hw/arm/strongarm.c index 0da9015333..cc2d7f20e9 100644 --- a/hw/arm/strongarm.c +++ b/hw/arm/strongarm.c @@ -480,7 +480,6 @@ struct StrongARMGPIOInfo { uint32_t rising; uint32_t falling; uint32_t status; - uint32_t gpsr; uint32_t gafr; uint32_t prev_level; @@ -544,14 +543,14 @@ static uint64_t strongarm_gpio_read(void *opaque, hwaddr offset, return s->dir; case GPSR: /* GPIO Pin-Output Set registers */ - DPRINTF("%s: Read from a write-only register 0x" TARGET_FMT_plx "\n", - __func__, offset); - return s->gpsr; /* Return last written value. */ + qemu_log_mask(LOG_GUEST_ERROR, + "strongarm GPIO: read from write only register GPSR\n"); + return 0; case GPCR: /* GPIO Pin-Output Clear registers */ - DPRINTF("%s: Read from a write-only register 0x" TARGET_FMT_plx "\n", - __func__, offset); - return 31337; /* Specified as unpredictable in the docs. */ + qemu_log_mask(LOG_GUEST_ERROR, + "strongarm GPIO: read from write only register GPCR\n"); + return 0; case GRER: /* GPIO Rising-Edge Detect Enable registers */ return s->rising; @@ -590,7 +589,6 @@ static void strongarm_gpio_write(void *opaque, hwaddr offset, case GPSR: /* GPIO Pin-Output Set registers */ s->olevel |= value; strongarm_gpio_handler_update(s); - s->gpsr = value; break; case GPCR: /* GPIO Pin-Output Clear registers */ -- GitLab