From a76e6542d1ab39ca50777f3fd0146151d0868c5c Mon Sep 17 00:00:00 2001 From: Tristan Shieh Date: Mon, 8 Apr 2019 11:01:40 +0800 Subject: mediatek: Use the 64-bit timer GPT4 is a 32-bit timer and the counter of GPT4 will overflow in about 330 seconds (0xffffffff / 13MHz). Timer and delay functions will not work properly if the counter overflows. To fix that we should use the 64-bit timer (GPT6). BUG=b:80501386 BRANCH=none Test=emerge-elm coreboot; emerge-kukui coreboot Change-Id: I9f080e47253a1b1bab4636a45cb86c8666a25302 Signed-off-by: Tristan Shieh Reviewed-on: https://review.coreboot.org/c/coreboot/+/32245 Tested-by: build bot (Jenkins) Reviewed-by: Hung-Te Lin Reviewed-by: Julius Werner Reviewed-by: You-Cheng Syu --- src/soc/mediatek/common/timer.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) (limited to 'src/soc/mediatek/common/timer.c') diff --git a/src/soc/mediatek/common/timer.c b/src/soc/mediatek/common/timer.c index 0762c2b4b4..c8af2be113 100644 --- a/src/soc/mediatek/common/timer.c +++ b/src/soc/mediatek/common/timer.c @@ -25,21 +25,34 @@ static struct mtk_gpt_regs *const mtk_gpt = (void *)GPT_BASE; __weak void timer_prepare(void) { /* do nothing */ } +static uint64_t timer_raw_value(void) +{ + /* + * According to "General-Purpose Timer (GPT).pdf", The read operation of + * gpt6_cnt_l will make gpt6_cnt_h fixed until the next read operation + * of gpt6_cnt_l. Therefore, we must read gpt6_cnt_l before gpt6_cnt_h. + */ + uint32_t low = read32(&mtk_gpt->gpt6_cnt_l); + uint32_t high = read32(&mtk_gpt->gpt6_cnt_h); + + return low | (uint64_t)high << 32; +} + void timer_monotonic_get(struct mono_time *mt) { - mono_time_set_usecs(mt, read32(&mtk_gpt->gpt4_cnt) / GPT4_MHZ); + mono_time_set_usecs(mt, timer_raw_value() / GPT_MHZ); } void init_timer(void) { timer_prepare(); - /* Disable GPT4 and clear the counter */ - clrbits_le32(&mtk_gpt->gpt4_con, GPT_CON_EN); - setbits_le32(&mtk_gpt->gpt4_con, GPT_CON_CLR); + /* Disable timer and clear the counter */ + clrbits_le32(&mtk_gpt->gpt6_con, GPT_CON_EN); + setbits_le32(&mtk_gpt->gpt6_con, GPT_CON_CLR); /* Set clock source to system clock and set clock divider to 1 */ - write32(&mtk_gpt->gpt4_clk, GPT_SYS_CLK | GPT_CLK_DIV1); - /* Set operation mode to FREERUN mode and enable GTP4 */ - write32(&mtk_gpt->gpt4_con, GPT_CON_EN | GPT_MODE_FREERUN); + write32(&mtk_gpt->gpt6_clk, GPT_SYS_CLK | GPT_CLK_DIV1); + /* Set operation mode to FREERUN mode and enable timer */ + write32(&mtk_gpt->gpt6_con, GPT_CON_EN | GPT_MODE_FREERUN); } -- cgit v1.2.3