1 files changed, 77 insertions, 4 deletions

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index ed3113576740..51b307aab75e 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -62,6 +62,70 @@ struct dw8250_data {
 	struct uart_8250_dma	dma;
 };
 
+struct dw8250_acpi_desc {
+	void (*set_termios)(struct uart_port *p, struct ktermios *termios,
+			    struct ktermios *old);
+};
+
+#define BYT_PRV_CLK			0x800
+#define BYT_PRV_CLK_EN			(1 << 0)
+#define BYT_PRV_CLK_M_VAL_SHIFT		1
+#define BYT_PRV_CLK_N_VAL_SHIFT		16
+#define BYT_PRV_CLK_UPDATE		(1 << 31)
+
+static void byt_set_termios(struct uart_port *p, struct ktermios *termios,
+			    struct ktermios *old)
+{
+	unsigned int baud = tty_termios_baud_rate(termios);
+	unsigned int m, n;
+	u32 reg;
+
+	/*
+	* For baud rates 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M and 4M the
+	* dividers must be adjusted.
+	*
+	* uartclk = (m / n) * 100 MHz, where m <= n
+	*/
+	switch (baud) {
+	case 500000:
+	case 1000000:
+	case 2000000:
+	case 4000000:
+		m = 64;
+		n = 100;
+		p->uartclk = 64000000;
+		break;
+	case 3500000:
+		m = 56;
+		n = 100;
+		p->uartclk = 56000000;
+		break;
+	case 1500000:
+	case 3000000:
+		m = 48;
+		n = 100;
+		p->uartclk = 48000000;
+		break;
+	case 2500000:
+		m = 40;
+		n = 100;
+		p->uartclk = 40000000;
+		break;
+	default:
+		m = 2304;
+		n = 3125;
+		p->uartclk = 73728000;
+	}
+
+	/* Reset the clock */
+	reg = (m << BYT_PRV_CLK_M_VAL_SHIFT) | (n << BYT_PRV_CLK_N_VAL_SHIFT);
+	writel(reg, p->membase + BYT_PRV_CLK);
+	reg |= BYT_PRV_CLK_EN | BYT_PRV_CLK_UPDATE;
+	writel(reg, p->membase + BYT_PRV_CLK);
+
+	serial8250_do_set_termios(p, termios, old);
+}
+
 static inline int dw8250_modify_msr(struct uart_port *p, int offset, int value)
 {
 	struct dw8250_data *d = p->private_data;
@@ -278,6 +342,7 @@ static int dw8250_probe_acpi(struct uart_8250_port *up,
 {
 	const struct acpi_device_id *id;
 	struct uart_port *p = &up->port;
+	struct dw8250_acpi_desc *acpi_desc;
 
 	dw8250_setup_port(up);
 
@@ -290,14 +355,18 @@ static int dw8250_probe_acpi(struct uart_8250_port *up,
 	p->serial_out = dw8250_serial_out32;
 	p->regshift = 2;
 
-	if (!p->uartclk)
-		p->uartclk = (unsigned int)id->driver_data;
-
 	up->dma = &data->dma;
 
 	up->dma->rxconf.src_maxburst = p->fifosize / 4;
 	up->dma->txconf.dst_maxburst = p->fifosize / 4;
 
+	acpi_desc = (struct dw8250_acpi_desc *)id->driver_data;
+	if (!acpi_desc)
+		return 0;
+
+	if (acpi_desc->set_termios)
+		p->set_termios = acpi_desc->set_termios;
+
 	return 0;
 }
 
@@ -445,12 +514,16 @@ static const struct of_device_id dw8250_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, dw8250_of_match);
 
+static struct dw8250_acpi_desc byt_8250_desc = {
+	.set_termios = byt_set_termios,
+};
+
 static const struct acpi_device_id dw8250_acpi_match[] = {
 	{ "INT33C4", 0 },
 	{ "INT33C5", 0 },
 	{ "INT3434", 0 },
 	{ "INT3435", 0 },
-	{ "80860F0A", 0 },
+	{ "80860F0A", (kernel_ulong_t)&byt_8250_desc},
 	{ },
 };
 MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match);