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-rw-r--r--drivers/tty/serial/xilinx_uartps.c136
1 files changed, 93 insertions, 43 deletions
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index fdc739b55eb3..95e12c216984 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -156,6 +156,11 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255");
#define XUARTPS_SR_TXFULL 0x00000010 /* TX FIFO full */
#define XUARTPS_SR_RXTRIG 0x00000001 /* Rx Trigger */
+/* baud dividers min/max values */
+#define XUARTPS_BDIV_MIN 4
+#define XUARTPS_BDIV_MAX 255
+#define XUARTPS_CD_MAX 65535
+
/**
* struct xuartps - device data
* @refclk Reference clock
@@ -305,59 +310,94 @@ static irqreturn_t xuartps_isr(int irq, void *dev_id)
}
/**
- * xuartps_set_baud_rate - Calculate and set the baud rate
- * @port: Handle to the uart port structure
- * @baud: Baud rate to set
- *
+ * xuartps_calc_baud_divs - Calculate baud rate divisors
+ * @clk: UART module input clock
+ * @baud: Desired baud rate
+ * @rbdiv: BDIV value (return value)
+ * @rcd: CD value (return value)
+ * @div8: Value for clk_sel bit in mod (return value)
* Returns baud rate, requested baud when possible, or actual baud when there
- * was too much error
- **/
-static unsigned int xuartps_set_baud_rate(struct uart_port *port,
- unsigned int baud)
+ * was too much error, zero if no valid divisors are found.
+ *
+ * Formula to obtain baud rate is
+ * baud_tx/rx rate = clk/CD * (BDIV + 1)
+ * input_clk = (Uart User Defined Clock or Apb Clock)
+ * depends on UCLKEN in MR Reg
+ * clk = input_clk or input_clk/8;
+ * depends on CLKS in MR reg
+ * CD and BDIV depends on values in
+ * baud rate generate register
+ * baud rate clock divisor register
+ */
+static unsigned int xuartps_calc_baud_divs(unsigned int clk, unsigned int baud,
+ u32 *rbdiv, u32 *rcd, int *div8)
{
- unsigned int sel_clk;
- unsigned int calc_baud = 0;
- unsigned int brgr_val, brdiv_val;
+ u32 cd, bdiv;
+ unsigned int calc_baud;
+ unsigned int bestbaud = 0;
unsigned int bauderror;
+ unsigned int besterror = ~0;
- /* Formula to obtain baud rate is
- * baud_tx/rx rate = sel_clk/CD * (BDIV + 1)
- * input_clk = (Uart User Defined Clock or Apb Clock)
- * depends on UCLKEN in MR Reg
- * sel_clk = input_clk or input_clk/8;
- * depends on CLKS in MR reg
- * CD and BDIV depends on values in
- * baud rate generate register
- * baud rate clock divisor register
- */
- sel_clk = port->uartclk;
- if (xuartps_readl(XUARTPS_MR_OFFSET) & XUARTPS_MR_CLKSEL)
- sel_clk = sel_clk / 8;
-
- /* Find the best values for baud generation */
- for (brdiv_val = 4; brdiv_val < 255; brdiv_val++) {
+ if (baud < clk / ((XUARTPS_BDIV_MAX + 1) * XUARTPS_CD_MAX)) {
+ *div8 = 1;
+ clk /= 8;
+ } else {
+ *div8 = 0;
+ }
- brgr_val = sel_clk / (baud * (brdiv_val + 1));
- if (brgr_val < 2 || brgr_val > 65535)
+ for (bdiv = XUARTPS_BDIV_MIN; bdiv <= XUARTPS_BDIV_MAX; bdiv++) {
+ cd = DIV_ROUND_CLOSEST(clk, baud * (bdiv + 1));
+ if (cd < 1 || cd > XUARTPS_CD_MAX)
continue;
- calc_baud = sel_clk / (brgr_val * (brdiv_val + 1));
+ calc_baud = clk / (cd * (bdiv + 1));
if (baud > calc_baud)
bauderror = baud - calc_baud;
else
bauderror = calc_baud - baud;
- /* use the values when percent error is acceptable */
- if (((bauderror * 100) / baud) < 3) {
- calc_baud = baud;
- break;
+ if (besterror > bauderror) {
+ *rbdiv = bdiv;
+ *rcd = cd;
+ bestbaud = calc_baud;
+ besterror = bauderror;
}
}
+ /* use the values when percent error is acceptable */
+ if (((besterror * 100) / baud) < 3)
+ bestbaud = baud;
+
+ return bestbaud;
+}
- /* Set the values for the new baud rate */
- xuartps_writel(brgr_val, XUARTPS_BAUDGEN_OFFSET);
- xuartps_writel(brdiv_val, XUARTPS_BAUDDIV_OFFSET);
+/**
+ * xuartps_set_baud_rate - Calculate and set the baud rate
+ * @port: Handle to the uart port structure
+ * @baud: Baud rate to set
+ * Returns baud rate, requested baud when possible, or actual baud when there
+ * was too much error, zero if no valid divisors are found.
+ */
+static unsigned int xuartps_set_baud_rate(struct uart_port *port,
+ unsigned int baud)
+{
+ unsigned int calc_baud;
+ u32 cd, bdiv;
+ u32 mreg;
+ int div8;
+
+ calc_baud = xuartps_calc_baud_divs(port->uartclk, baud, &bdiv, &cd,
+ &div8);
+
+ /* Write new divisors to hardware */
+ mreg = xuartps_readl(XUARTPS_MR_OFFSET);
+ if (div8)
+ mreg |= XUARTPS_MR_CLKSEL;
+ else
+ mreg &= ~XUARTPS_MR_CLKSEL;
+ xuartps_writel(mreg, XUARTPS_MR_OFFSET);
+ xuartps_writel(cd, XUARTPS_BAUDGEN_OFFSET);
+ xuartps_writel(bdiv, XUARTPS_BAUDDIV_OFFSET);
return calc_baud;
}
@@ -495,7 +535,7 @@ static void xuartps_set_termios(struct uart_port *port,
struct ktermios *termios, struct ktermios *old)
{
unsigned int cval = 0;
- unsigned int baud;
+ unsigned int baud, minbaud, maxbaud;
unsigned long flags;
unsigned int ctrl_reg, mode_reg;
@@ -512,8 +552,14 @@ static void xuartps_set_termios(struct uart_port *port,
(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS),
XUARTPS_CR_OFFSET);
- /* Min baud rate = 6bps and Max Baud Rate is 10Mbps for 100Mhz clk */
- baud = uart_get_baud_rate(port, termios, old, 0, 10000000);
+ /*
+ * Min baud rate = 6bps and Max Baud Rate is 10Mbps for 100Mhz clk
+ * min and max baud should be calculated here based on port->uartclk.
+ * this way we get a valid baud and can safely call set_baud()
+ */
+ minbaud = port->uartclk / ((XUARTPS_BDIV_MAX + 1) * XUARTPS_CD_MAX * 8);
+ maxbaud = port->uartclk / (XUARTPS_BDIV_MIN + 1);
+ baud = uart_get_baud_rate(port, termios, old, minbaud, maxbaud);
baud = xuartps_set_baud_rate(port, baud);
if (tty_termios_baud_rate(termios))
tty_termios_encode_baud_rate(termios, baud, baud);
@@ -589,13 +635,17 @@ static void xuartps_set_termios(struct uart_port *port,
cval |= XUARTPS_MR_PARITY_MARK;
else
cval |= XUARTPS_MR_PARITY_SPACE;
- } else if (termios->c_cflag & PARODD)
+ } else {
+ if (termios->c_cflag & PARODD)
cval |= XUARTPS_MR_PARITY_ODD;
else
cval |= XUARTPS_MR_PARITY_EVEN;
- } else
+ }
+ } else {
cval |= XUARTPS_MR_PARITY_NONE;
- xuartps_writel(cval , XUARTPS_MR_OFFSET);
+ }
+ cval |= mode_reg & 1;
+ xuartps_writel(cval, XUARTPS_MR_OFFSET);
spin_unlock_irqrestore(&port->lock, flags);
}