-From d8bde59186dafdea5bbe8d29d3a6ae7cac98e9d0 Mon Sep 17 00:00:00 2001
-From: Weijie Gao <weijie.gao@mediatek.com>
-Date: Mon, 25 Jan 2021 11:19:08 +0800
-Subject: [PATCH 11/21] serial: serial-mtk: rewrite the setbrg function
-
-Currently the setbrg logic of serial-mtk is messy, and should be rewritten.
-Also an option is added to make it possible to use highspeed=3 mode for all
-bauds.
-
-The new logic is:
-1. If baud clock > 12MHz
- a) If baud <= 115200, highspeed=0 mode will be used (ns16550 compatible)
- b) If baud <= 576000, highspeed=2 mode will be used
- c) any baud > 576000, highspeed=3 mode will be used
-2. If baud clock <= 12MHz
- Always uses highspeed=3 mode
- a) If baud <= 115200, calculates the divisor using DIV_ROUND_CLOSEST
- b) any baud > 115200, the same as 1. c)
-
-Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
----
- drivers/serial/serial_mtk.c | 74 +++++++++++++++++--------------------
- 1 file changed, 33 insertions(+), 41 deletions(-)
-
---- a/drivers/serial/serial_mtk.c
-+++ b/drivers/serial/serial_mtk.c
-@@ -73,74 +73,64 @@ struct mtk_serial_regs {
- struct mtk_serial_priv {
- struct mtk_serial_regs __iomem *regs;
- u32 clock;
-+ bool force_highspeed;
- };
-
- static void _mtk_serial_setbrg(struct mtk_serial_priv *priv, int baud)
- {
-- bool support_clk12m_baud115200;
-- u32 quot, samplecount, realbaud;
-+ u32 quot, realbaud, samplecount = 1;
-
-- if ((baud <= 115200) && (priv->clock == 12000000))
-- support_clk12m_baud115200 = true;
-- else
-- support_clk12m_baud115200 = false;
-+ /* Special case for low baud clock */
-+ if ((baud <= 115200) && (priv->clock == 12000000)) {
-+ writel(3, &priv->regs->highspeed);
-+
-+ quot = DIV_ROUND_CLOSEST(priv->clock, 256 * baud);
-+ if (quot == 0)
-+ quot = 1;
-+
-+ samplecount = DIV_ROUND_CLOSEST(priv->clock, quot * baud);
-+
-+ realbaud = priv->clock / samplecount / quot;
-+ if ((realbaud > BAUD_ALLOW_MAX(baud)) ||
-+ (realbaud < BAUD_ALLOW_MIX(baud))) {
-+ pr_info("baud %d can't be handled\n", baud);
-+ }
-+
-+ goto set_baud;
-+ }
-+
-+ if (priv->force_highspeed)
-+ goto use_hs3;
-
- if (baud <= 115200) {
- writel(0, &priv->regs->highspeed);
- quot = DIV_ROUND_CLOSEST(priv->clock, 16 * baud);
--
-- if (support_clk12m_baud115200) {
-- writel(3, &priv->regs->highspeed);
-- quot = DIV_ROUND_CLOSEST(priv->clock, 256 * baud);
-- if (quot == 0)
-- quot = 1;
--
-- samplecount = DIV_ROUND_CLOSEST(priv->clock,
-- quot * baud);
-- if (samplecount != 0) {
-- realbaud = priv->clock / samplecount / quot;
-- if ((realbaud > BAUD_ALLOW_MAX(baud)) ||
-- (realbaud < BAUD_ALLOW_MIX(baud))) {
-- pr_info("baud %d can't be handled\n",
-- baud);
-- }
-- } else {
-- pr_info("samplecount is 0\n");
-- }
-- }
- } else if (baud <= 576000) {
- writel(2, &priv->regs->highspeed);
-
- /* Set to next lower baudrate supported */
- if ((baud == 500000) || (baud == 576000))
- baud = 460800;
-+
- quot = DIV_ROUND_UP(priv->clock, 4 * baud);
- } else {
-+use_hs3:
- writel(3, &priv->regs->highspeed);
-+
- quot = DIV_ROUND_UP(priv->clock, 256 * baud);
-+ samplecount = DIV_ROUND_CLOSEST(priv->clock, quot * baud);
- }
-
-+set_baud:
- /* set divisor */
- writel(UART_LCR_WLS_8 | UART_LCR_DLAB, &priv->regs->lcr);
- writel(quot & 0xff, &priv->regs->dll);
- writel((quot >> 8) & 0xff, &priv->regs->dlm);
- writel(UART_LCR_WLS_8, &priv->regs->lcr);
-
-- if (baud > 460800) {
-- u32 tmp;
--
-- tmp = DIV_ROUND_CLOSEST(priv->clock, quot * baud);
-- writel(tmp - 1, &priv->regs->sample_count);
-- writel((tmp - 2) >> 1, &priv->regs->sample_point);
-- } else {
-- writel(0, &priv->regs->sample_count);
-- writel(0xff, &priv->regs->sample_point);
-- }
--
-- if (support_clk12m_baud115200) {
-- writel(samplecount - 1, &priv->regs->sample_count);
-- writel((samplecount - 2) >> 1, &priv->regs->sample_point);
-- }
-+ /* set highspeed mode sample count & point */
-+ writel(samplecount - 1, &priv->regs->sample_count);
-+ writel((samplecount - 2) >> 1, &priv->regs->sample_point);
- }
-
- static int _mtk_serial_putc(struct mtk_serial_priv *priv, const char ch)
-@@ -248,6 +238,8 @@ static int mtk_serial_of_to_plat(struct
- return -EINVAL;
- }
-
-+ priv->force_highspeed = dev_read_bool(dev, "mediatek,force-highspeed");
-+
- return 0;
- }
-
projects / openwrt / staging / hauke.git / commitdiff