linux-kernel - [PATCH v2 6/6] tty: serial: msm: Remove 115.2 Kbps maximum baud rate limitation

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Message-Id: <1443614906-2196-7-git-send-email-ivan.ivanov@linaro.org>
Date:	Wed, 30 Sep 2015 15:08:26 +0300
From:	"Ivan T. Ivanov" <ivan.ivanov@...aro.org>
To:	Andy Gross <agross@...eaurora.org>
Cc:	David Brown <davidb@...eaurora.org>,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.com>,
	Frank Rowand <frank.rowand@...ymobile.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
	linux-serial@...r.kernel.org
Subject: [PATCH v2 6/6] tty: serial: msm: Remove 115.2 Kbps maximum baud rate limitation

UART controller is capable to perform transfers up to 4 Mbps.
Remove artificial 115.2 Kbps limitation.

Signed-off-by: Ivan T. Ivanov <ivan.ivanov@...aro.org>
---
 drivers/tty/serial/msm_serial.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index fc5f6b3b4bbb..abeb35555d93 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -882,6 +882,7 @@ msm_find_best_baud(struct uart_port *port, unsigned int baud)
 		{    3, 0xdd,  8 },
 		{    2, 0xee, 16 },
 		{    1, 0xff, 31 },
+		{    0, 0xff, 31 },
 	};

 	divisor = uart_get_divisor(port, baud);
@@ -893,16 +894,29 @@ msm_find_best_baud(struct uart_port *port, unsigned int baud)
 	return entry; /* Default to smallest divider */
 }

-static int msm_set_baud_rate(struct uart_port *port, unsigned int baud)
+static int msm_set_baud_rate(struct uart_port *port, unsigned int baud,
+			     unsigned long *saved_flags)
 {
 	unsigned int rxstale, watermark, mask;
 	struct msm_port *msm_port = UART_TO_MSM(port);
 	const struct msm_baud_map *entry;
+	unsigned long flags;

 	entry = msm_find_best_baud(port, baud);

 	msm_write(port, entry->code, UART_CSR);

+	if (baud > 460800)
+		port->uartclk = baud * 16;
+
+	flags = *saved_flags;
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	clk_set_rate(msm_port->clk, port->uartclk);
+
+	spin_lock_irqsave(&port->lock, flags);
+	*saved_flags = flags;
+
 	/* RX stale watermark */
 	rxstale = entry->rxstale;
 	watermark = UART_IPR_STALE_LSB & rxstale;
@@ -1026,8 +1040,8 @@ static void msm_set_termios(struct uart_port *port, struct ktermios *termios,
 		msm_stop_dma(port, dma);

 	/* calculate and set baud rate */
-	baud = uart_get_baud_rate(port, termios, old, 300, 115200);
-	baud = msm_set_baud_rate(port, baud);
+	baud = uart_get_baud_rate(port, termios, old, 300, 4000000);
+	baud = msm_set_baud_rate(port, baud, &flags);
 	if (tty_termios_baud_rate(termios))
 		tty_termios_encode_baud_rate(termios, baud, baud);

--
1.9.1

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