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driver: timer: npcx: add check for system kernel timer frequency

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In npcx series, we use ITIM64 as system kernel timer. Its source clock
frequency must equal to CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC. This CL
added check during initialization to prevent ambiguous condition.

Signed-off-by: Mulin Chao <mlchao@nuvoton.com>
This commit is contained in:
Mulin Chao 2021-05-25 23:09:50 -07:00 • committed by Anas Nashif
commit 6885afe432
1 changed files with 18 additions and 0 deletions
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18
drivers/timer/npcx_itim_timer.c
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@ -271,6 +271,7 @@ int sys_clock_driver_init(const struct device *dev)
{
ARG_UNUSED(dev);
int ret;
uint32_t sys_tmr_rate;
const struct device *const clk_dev =
device_get_binding(NPCX_CLK_CTRL_NAME);
@ -284,6 +285,23 @@ int sys_clock_driver_init(const struct device *dev)
}
}
/*
* In npcx series, we use ITIM64 as system kernel timer. Its source
* clock frequency must equal to CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC.
*/
ret = clock_control_get_rate(clk_dev, (clock_control_subsys_t *)
&itim_clk_cfg[1], &sys_tmr_rate);
if (ret < 0) {
LOG_ERR("Get ITIM64 clock rate failed %d", ret);
return ret;
}
if (sys_tmr_rate != CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC) {
LOG_ERR("CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC doesn't match "
"ITIM64 clock frequency %d", sys_tmr_rate);
return -EINVAL;
}
/*
* Step 1. Use a ITIM64 timer as system kernel timer for counting.
* Configure 64-bit timer counter and its prescaler to 1 first.