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[v3,06/12] Serial: OMAP2+: Move erratum handling from serial.c

Message ID 1307532194-13039-7-git-send-email-govindraj.raja@ti.com (mailing list archive)
State New, archived
Headers show

Commit Message

Govindraj.R June 8, 2011, 11:23 a.m. UTC 
Move the erratum handling mechanism from serial.c to driver file
and utilise the same func. in driver file.

Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
---
 drivers/tty/serial/omap-serial.c |   57 ++++++++++++++++++++++++++++++++++---
 1 files changed, 52 insertions(+), 5 deletions(-)
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Patch

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index ee94291..2ad8fa0 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -52,6 +52,7 @@  static struct uart_omap_port *ui[OMAP_MAX_HSUART_PORTS];
 static void uart_tx_dma_callback(int lch, u16 ch_status, void *data);
 static void serial_omap_rx_timeout(unsigned long uart_no);
 static int serial_omap_start_rxdma(struct uart_omap_port *up);
+static void omap_uart_mdr1_errataset(struct uart_omap_port *up, u8 mdr1);
 
 static inline unsigned int serial_in(struct uart_omap_port *up, int offset)
 {
@@ -807,7 +808,11 @@  serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
 	serial_out(up, UART_MCR, up->mcr);
 
 	/* Protocol, Baud Rate, and Interrupt Settings */
-	serial_out(up, UART_OMAP_MDR1, up->mdr1);
+	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
+		omap_uart_mdr1_errataset(up, up->mdr1);
+	else
+		serial_out(up, UART_OMAP_MDR1, up->mdr1);
+
 	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
 
 	up->efr = serial_in(up, UART_EFR);
@@ -832,7 +837,10 @@  serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
 	else
 		up->mdr1 = UART_OMAP_MDR1_16X_MODE;
 
-	serial_out(up, UART_OMAP_MDR1, up->mdr1)
+	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
+		omap_uart_mdr1_errataset(up, up->mdr1);
+	else
+		serial_out(up, UART_OMAP_MDR1, up->mdr1);
 
 	/* Hardware Flow Control Configuration */
 
@@ -1447,11 +1455,48 @@  static int serial_omap_remove(struct platform_device *dev)
 	return 0;
 }
 
+/*
+ * Work Around for Errata i202 (3430 - 1.12, 3630 - 1.6)
+ * The access to uart register after MDR1 Access
+ * causes UART to corrupt data.
+ *
+ * Need a delay =
+ * 5 L4 clock cycles + 5 UART functional clock cycle (@48MHz = ~0.2uS)
+ * give 10 times as much
+ */
+static void omap_uart_mdr1_errataset(struct uart_omap_port *up, u8 mdr1)
+{
+	u8 timeout = 255;
+
+	serial_out(up, UART_OMAP_MDR1, mdr1);
+	udelay(2);
+	serial_out(up, UART_FCR, up->fcr | UART_FCR_CLEAR_XMIT |
+			UART_FCR_CLEAR_RCVR);
+	/*
+	 * Wait for FIFO to empty: when empty, RX_FIFO_E bit is 0 and
+	 * TX_FIFO_E bit is 1.
+	 */
+	while (UART_LSR_THRE != (serial_in(up, UART_LSR) &
+				(UART_LSR_THRE | UART_LSR_DR))) {
+		timeout--;
+		if (!timeout) {
+			/* Should *never* happen. we warn and carry on */
+			dev_crit(&up->pdev->dev, "Errata i202: timedout %x\n",
+						serial_in(up, UART_LSR));
+			break;
+		}
+		udelay(1);
+	}
+}
+
 static void omap_uart_restore_context(struct uart_omap_port *up)
 {
 	u16 efr = 0;
 
-	serial_out(up, UART_OMAP_MDR1, up->mdr1);
+	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
+		omap_uart_mdr1_errataset(up, UART_OMAP_MDR1_DISABLE);
+	else
+		serial_out(up, UART_OMAP_MDR1, UART_OMAP_MDR1_DISABLE);
 	serial_out(up, UART_LCR, 0xBF); /* Config B mode */
 	efr = serial_in(up, UART_EFR);
 	serial_out(up, UART_EFR, UART_EFR_ECB);
@@ -1468,8 +1513,10 @@  static void omap_uart_restore_context(struct uart_omap_port *up)
 	serial_out(up, UART_LCR, 0xBF); /* Config B mode */
 	serial_out(up, UART_EFR, efr);
 	serial_out(up, UART_LCR, up->lcr);
-	/* UART 16x mode */
-	serial_out(up, UART_OMAP_MDR1, up->mdr1);
+	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
+		omap_uart_mdr1_errataset(up, up->mdr1);
+	else
+		serial_out(up, UART_OMAP_MDR1, up->mdr1);
 }
 
 static int omap_serial_runtime_suspend(struct device *dev)