From a54d259157e2575b69e2cf7cf03592c74559cb7e Mon Sep 17 00:00:00 2001 From: Green Wan Date: Tue, 20 Oct 2020 11:37:31 +0800 Subject: hw/misc/sifive_u_otp: Add write function and write-once protection - Add write operation to update fuse data bit when PWE bit is on. - Add array, fuse_wo, to store the 'written' status for all bits of OTP to block the write operation. Signed-off-by: Green Wan Reviewed-by: Alistair Francis Reviewed-by: Bin Meng Tested-by: Bin Meng Message-id: 20201020033732.12921-2-green.wan@sifive.com Signed-off-by: Alistair Francis --- hw/misc/sifive_u_otp.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'hw/misc') diff --git a/hw/misc/sifive_u_otp.c b/hw/misc/sifive_u_otp.c index c2f3c8e..b9238d6 100644 --- a/hw/misc/sifive_u_otp.c +++ b/hw/misc/sifive_u_otp.c @@ -25,6 +25,14 @@ #include "qemu/module.h" #include "hw/misc/sifive_u_otp.h" +#define WRITTEN_BIT_ON 0x1 + +#define SET_FUSEARRAY_BIT(map, i, off, bit) \ + map[i] = bit ? (map[i] | bit << off) : (map[i] & ~(0x1 << off)) + +#define GET_FUSEARRAY_BIT(map, i, off) \ + ((map[i] >> off) & 0x1) + static uint64_t sifive_u_otp_read(void *opaque, hwaddr addr, unsigned int size) { SiFiveUOTPState *s = opaque; @@ -123,7 +131,24 @@ static void sifive_u_otp_write(void *opaque, hwaddr addr, s->ptrim = val32; break; case SIFIVE_U_OTP_PWE: - s->pwe = val32; + s->pwe = val32 & SIFIVE_U_OTP_PWE_EN; + + /* PWE is enabled. Ignore PAS=1 (no redundancy cell) */ + if (s->pwe && !s->pas) { + if (GET_FUSEARRAY_BIT(s->fuse_wo, s->pa, s->paio)) { + qemu_log_mask(LOG_GUEST_ERROR, + "write once error: idx<%u>, bit<%u>\n", + s->pa, s->paio); + break; + } + + /* write bit data */ + SET_FUSEARRAY_BIT(s->fuse, s->pa, s->paio, s->pdin); + + /* update written bit */ + SET_FUSEARRAY_BIT(s->fuse_wo, s->pa, s->paio, WRITTEN_BIT_ON); + } + break; default: qemu_log_mask(LOG_GUEST_ERROR, "%s: bad write: addr=0x%" HWADDR_PRIx @@ -165,6 +190,9 @@ static void sifive_u_otp_reset(DeviceState *dev) /* Make a valid content of serial number */ s->fuse[SIFIVE_U_OTP_SERIAL_ADDR] = s->serial; s->fuse[SIFIVE_U_OTP_SERIAL_ADDR + 1] = ~(s->serial); + + /* Initialize write-once map */ + memset(s->fuse_wo, 0x00, sizeof(s->fuse_wo)); } static void sifive_u_otp_class_init(ObjectClass *klass, void *data) -- cgit v1.1