diff options
| author | Tom Rini <trini@konsulko.com> | 2025-06-05 14:31:02 -0600 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2025-06-05 16:57:35 -0600 |
| commit | 615997ec2174916be7ee214cf20e22978fdb34e8 (patch) | |
| tree | c44d1e7d136a3ee767e27487bb9f8b76eeb4c38a /drivers/serial/serial_mtk.c | |
| parent | bed3b33e732f2f2d9ce93801f7dbe09a02b52c3a (diff) | |
| parent | 6952209ef220138189dd261d06441e1b2d50e994 (diff) | |
Merge patch series "Add baudrate accuracy compensation for MediaTek UART driver"
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
Diffstat (limited to 'drivers/serial/serial_mtk.c')
| -rw-r--r-- | drivers/serial/serial_mtk.c | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/drivers/serial/serial_mtk.c b/drivers/serial/serial_mtk.c index becf9317076..01cc415efdd 100644 --- a/drivers/serial/serial_mtk.c +++ b/drivers/serial/serial_mtk.c @@ -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) |