From 6e138e4c3bfa5fb272d215107d85385456281ceb Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <lars@metafoo.de>
Date: Sat, 24 Apr 2010 12:19:30 +0200
Subject: [PATCH] Add jz4740 serial driver

---
 drivers/serial/8250.c |  104 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 103 insertions(+), 1 deletions(-)

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 2b1ea3d..4c41c57 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -200,7 +200,7 @@ static const struct serial8250_config uart_config[] = {
 	[PORT_16550A] = {
 		.name		= "16550A",
 		.fifo_size	= 16,
-		.tx_loadsz	= 16,
+		.tx_loadsz	= 8,
 		.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
 		.flags		= UART_CAP_FIFO,
 	},
@@ -407,6 +407,10 @@ static unsigned int mem_serial_in(struct uart_port *p, int offset)
 static void mem_serial_out(struct uart_port *p, int offset, int value)
 {
 	offset = map_8250_out_reg(p, offset) << p->regshift;
+#if defined(CONFIG_JZSOC)
+		if (offset == (UART_FCR << p->regshift))
+			value |= 0x10; /* set FCR.UUE */
+#endif
 	writeb(value, p->membase + offset);
 }
 
@@ -2209,6 +2213,83 @@ static void serial8250_shutdown(struct uart_port *port)
 		serial_unlink_irq_chain(up);
 }
 
+#if defined(CONFIG_JZSOC) && !defined(CONFIG_SOC_JZ4730)
+static unsigned short quot1[3] = {0}; /* quot[0]:baud_div, quot[1]:umr, quot[2]:uacr */
+static unsigned short * serial8250_get_divisor(struct uart_port *port, unsigned int baud)
+{
+	int err, sum, i, j;
+	int a[12], b[12];
+	unsigned short div, umr, uacr;
+	unsigned short umr_best, div_best, uacr_best;
+	long long t0, t1, t2, t3;
+
+	sum = 0;
+	umr_best = div_best = uacr_best = 0;
+	div = 1;
+
+	if ((port->uartclk % (16 * baud)) == 0) {
+		quot1[0] = port->uartclk / (16 * baud);
+		quot1[1] = 16;
+		quot1[2] = 0;
+		return quot1;
+	}
+
+	while (1) {
+		umr = port->uartclk / (baud * div);
+  		if (umr > 32) {
+			div++;
+			continue;
+		}
+		if (umr < 4) {
+			break;
+		}
+		for (i = 0; i < 12; i++) {
+			a[i] = umr;
+			b[i] = 0;
+			sum = 0;
+			for (j = 0; j <= i; j++) {
+				sum += a[j];
+			}
+
+                        /* the precision could be 1/2^(36) due to the value of t0 */
+			t0 = 0x1000000000LL;
+			t1 = (i + 1) * t0;
+			t2 = (sum * div) * t0;
+			t3 = div * t0;
+			do_div(t1, baud);
+			do_div(t2, port->uartclk);
+			do_div(t3, (2 * port->uartclk));
+			err = t1 - t2 - t3;
+
+			if (err > 0) {
+				a[i] += 1;
+				b[i] = 1;
+			}
+		}
+
+		uacr = 0;
+		for (i = 0; i < 12; i++) {
+			if (b[i] == 1) {
+				uacr |= 1 << i;
+			}
+		}
+
+                /* the best value of umr should be near 16, and the value of uacr should better be smaller */
+		if (abs(umr - 16) < abs(umr_best - 16) || (abs(umr - 16) == abs(umr_best - 16) && uacr_best > uacr)) {
+			div_best = div;
+			umr_best = umr;
+			uacr_best = uacr;
+		}
+		div++;
+	}
+
+	quot1[0] = div_best;
+	quot1[1] = umr_best;
+	quot1[2] = uacr_best;
+
+	return quot1;
+}
+#else
 static unsigned int serial8250_get_divisor(struct uart_port *port, unsigned int baud)
 {
 	unsigned int quot;
@@ -2228,6 +2309,7 @@ static unsigned int serial8250_get_divisor(struct uart_port *port, unsigned int
 
 	return quot;
 }
+#endif
 
 static void
 serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
@@ -2237,6 +2319,9 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
 	unsigned char cval, fcr = 0;
 	unsigned long flags;
 	unsigned int baud, quot;
+#if defined(CONFIG_JZSOC) && !defined(CONFIG_SOC_JZ4730)
+	unsigned short *quot1;
+#endif
 
 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
@@ -2271,7 +2356,12 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
 	baud = uart_get_baud_rate(port, termios, old,
 				  port->uartclk / 16 / 0xffff,
 				  port->uartclk / 16);
+#if defined(CONFIG_JZSOC) && !defined(CONFIG_SOC_JZ4730)
+	quot1 = serial8250_get_divisor(port, baud);
+	quot = quot1[0]; /* not usefull, just let gcc happy */
+#else
 	quot = serial8250_get_divisor(port, baud);
+#endif
 
 	/*
 	 * Oxford Semi 952 rev B workaround
@@ -2349,6 +2439,10 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
 	if (up->capabilities & UART_CAP_UUE)
 		up->ier |= UART_IER_UUE | UART_IER_RTOIE;
 
+#ifdef CONFIG_JZSOC
+	up->ier |= UART_IER_RTOIE; /* Set this flag, or very slow */
+#endif
+
 	serial_out(up, UART_IER, up->ier);
 
 	if (up->capabilities & UART_CAP_EFR) {
@@ -2383,7 +2477,15 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
 		serial_outp(up, UART_LCR, cval | UART_LCR_DLAB);/* set DLAB */
 	}
 
+#if defined(CONFIG_JZSOC) && !defined(CONFIG_SOC_JZ4730)
+#define UART_UMR  9
+#define UART_UACR 10
+	serial_dl_write(up, quot1[0]);
+	serial_outp(up, UART_UMR, quot1[1]);
+	serial_outp(up, UART_UACR, quot1[2]);
+#else
 	serial_dl_write(up, quot);
+#endif
 
 	/*
 	 * LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR
-- 
1.5.6.5

