[PATCH 6/7] tty: serial: fsl_lpuart: add LS1028A earlycon support

From: Michael Walle
Date: Thu Feb 20 2020 - 12:44:02 EST


Add a early_console_setup() for the LS1028A SoC with 32bit, little
endian access. If the bootloader does a fixup of the clock-frequency
node the baudrate divisor register will automatically be set.

Signed-off-by: Michael Walle <michael@xxxxxxxx>
---
drivers/tty/serial/fsl_lpuart.c | 51 +++++++++++++++++++++++++++------
1 file changed, 43 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 6953eea166dc..4386ffdfe275 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1834,11 +1834,12 @@ lpuart_set_termios(struct uart_port *port, struct ktermios *termios,
spin_unlock_irqrestore(&sport->port.lock, flags);
}

-static void
-lpuart32_serial_setbrg(struct lpuart_port *sport, unsigned int baudrate)
+static void __lpuart32_serial_setbrg(struct uart_port *port,
+ unsigned int baudrate, bool use_rx_dma,
+ bool use_tx_dma)
{
u32 sbr, osr, baud_diff, tmp_osr, tmp_sbr, tmp_diff, tmp;
- u32 clk = sport->port.uartclk;
+ u32 clk = port->uartclk;

/*
* The idea is to use the best OSR (over-sampling rate) possible.
@@ -1884,10 +1885,10 @@ lpuart32_serial_setbrg(struct lpuart_port *sport, unsigned int baudrate)

/* handle buadrate outside acceptable rate */
if (baud_diff > ((baudrate / 100) * 3))
- dev_warn(sport->port.dev,
+ dev_warn(port->dev,
"unacceptable baud rate difference of more than 3%%\n");

- tmp = lpuart32_read(&sport->port, UARTBAUD);
+ tmp = lpuart32_read(port, UARTBAUD);

if ((osr > 3) && (osr < 8))
tmp |= UARTBAUD_BOTHEDGE;
@@ -1898,14 +1899,23 @@ lpuart32_serial_setbrg(struct lpuart_port *sport, unsigned int baudrate)
tmp &= ~UARTBAUD_SBR_MASK;
tmp |= sbr & UARTBAUD_SBR_MASK;

- if (!sport->lpuart_dma_rx_use)
+ if (!use_rx_dma)
tmp &= ~UARTBAUD_RDMAE;
- if (!sport->lpuart_dma_tx_use)
+ if (!use_tx_dma)
tmp &= ~UARTBAUD_TDMAE;

- lpuart32_write(&sport->port, tmp, UARTBAUD);
+ lpuart32_write(port, tmp, UARTBAUD);
+}
+
+static void lpuart32_serial_setbrg(struct lpuart_port *sport,
+ unsigned int baudrate)
+{
+ __lpuart32_serial_setbrg(&sport->port, baudrate,
+ sport->lpuart_dma_rx_use,
+ sport->lpuart_dma_tx_use);
}

+
static void
lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
@@ -2399,6 +2409,30 @@ static int __init lpuart32_early_console_setup(struct earlycon_device *device,
return 0;
}

+static int __init ls1028a_early_console_setup(struct earlycon_device *device,
+ const char *opt)
+{
+ u32 cr;
+
+ if (!device->port.membase)
+ return -ENODEV;
+
+ device->port.iotype = UPIO_MEM32;
+ device->con->write = lpuart32_early_write;
+
+ /* set the baudrate */
+ if (device->port.uartclk && device->baud)
+ __lpuart32_serial_setbrg(&device->port, device->baud,
+ false, false);
+
+ /* enable transmitter */
+ cr = lpuart32_read(&device->port, UARTCTRL);
+ cr |= UARTCTRL_TE;
+ lpuart32_write(&device->port, cr, UARTCTRL);
+
+ return 0;
+}
+
static int __init lpuart32_imx_early_console_setup(struct earlycon_device *device,
const char *opt)
{
@@ -2413,6 +2447,7 @@ static int __init lpuart32_imx_early_console_setup(struct earlycon_device *devic
}
OF_EARLYCON_DECLARE(lpuart, "fsl,vf610-lpuart", lpuart_early_console_setup);
OF_EARLYCON_DECLARE(lpuart32, "fsl,ls1021a-lpuart", lpuart32_early_console_setup);
+OF_EARLYCON_DECLARE(lpuart32, "fsl,ls1028a-lpuart", ls1028a_early_console_setup);
OF_EARLYCON_DECLARE(lpuart32, "fsl,imx7ulp-lpuart", lpuart32_imx_early_console_setup);
EARLYCON_DECLARE(lpuart, lpuart_early_console_setup);
EARLYCON_DECLARE(lpuart32, lpuart32_early_console_setup);
--
2.20.1