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Merge patch series "Add baudrate accuracy compensation for MediaTek UART driver"

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Weijie Gao <weijie.gao@mediatek.com> says:

This patch series adds baudrate accuracy compensation for MediaTek UART
driver in high-speed mode 3.

Link: https://lore.kernel.org/r/cover.1747991898.git.weijie.gao@mediatek.com
This commit is contained in:
Tom Rini
2025-06-05 14:31:02 -06:00
parent bed3b33e73 6952209ef2
commit 615997ec21
1 changed files with 33 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

41
drivers/serial/serial_mtk.c
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@@ -30,16 +30,23 @@ struct mtk_serial_regs {
u32 mcr;
u32 lsr;
u32 msr;
u32 spr;
u32 mdr1;
u32 scr;
u32 autobaud_en;
u32 highspeed;
u32 sample_count;
u32 sample_point;
u32 autobaud_reg;
u32 ratefix_ad;
u32 autobaud_sample;
u32 guard;
u32 escape_dat;
u32 escape_en;
u32 sleep_en;
u32 dma_en;
u32 rxtri_ad;
u32 fracdiv_l;
u32 fracdiv_m;
u32 escape_en;
u32 guard;
u32 rx_sel;
u32 fcr_rd;
};
#define thr rbr
@@ -92,10 +99,18 @@ struct mtk_serial_priv {
bool upstream_highspeed_logic;
};
static const unsigned short fraction_l_mapping[] = {
0, 1, 0x5, 0x15, 0x55, 0x57, 0x57, 0x77, 0x7F, 0xFF, 0xFF
};
static const unsigned short fraction_m_mapping[] = {
0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 3
};
static void _mtk_serial_setbrg(struct mtk_serial_priv *priv, int baud,
uint clk_rate)
{
u32 quot, realbaud, samplecount = 1;
u32 quot, realbaud, samplecount = 1, fraction, frac_l = 0, frac_m = 0;
/* Special case for low baud clock */
if (baud <= 115200 && clk_rate == 12000000) {
@@ -140,7 +155,13 @@ use_hs3:
writel(3, &priv->regs->highspeed);
quot = DIV_ROUND_UP(clk_rate, 256 * baud);
samplecount = DIV_ROUND_CLOSEST(clk_rate, quot * baud);
samplecount = clk_rate / (quot * baud);
fraction = ((clk_rate * 100) / quot / baud) % 100;
fraction = DIV_ROUND_CLOSEST(fraction, 10);
frac_l = fraction_l_mapping[fraction];
frac_m = fraction_m_mapping[fraction];
}
set_baud:
@@ -152,7 +173,11 @@ set_baud:
/* set highspeed mode sample count & point */
writel(samplecount - 1, &priv->regs->sample_count);
writel((samplecount - 2) >> 1, &priv->regs->sample_point);
writel((samplecount >> 1) - 1, &priv->regs->sample_point);
/* set baudrate fraction compensation */
writel(frac_l, &priv->regs->fracdiv_l);
writel(frac_m, &priv->regs->fracdiv_m);
}
static int _mtk_serial_putc(struct mtk_serial_priv *priv, const char ch)