[PATCH 13/20] i.MX: Add 'lpuart' serial driver
Andrey Smirnov
andrew.smirnov at gmail.com
Mon Oct 3 07:40:50 PDT 2016
Add 'lpuart' serial driver, based on analogous driver from U-Boot
Signed-off-by: Andrey Smirnov <andrew.smirnov at gmail.com>
---
drivers/serial/Kconfig | 4 +
drivers/serial/Makefile | 1 +
drivers/serial/serial_lpuart.c | 217 +++++++++++++++++++++++++++++++++++++++++
include/serial/lpuart.h | 28 ++++--
4 files changed, 244 insertions(+), 6 deletions(-)
create mode 100644 drivers/serial/serial_lpuart.c
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 146bf1e..02e869a 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -137,4 +137,8 @@ config DRIVER_SERIAL_DIGIC
bool "Canon DIGIC serial driver"
depends on ARCH_DIGIC
+config DRIVER_SERIAL_LPUART
+ depends on ARCH_IMX
+ bool "LPUART serial driver"
+
endmenu
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 189e777..7d1bae1 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_DRIVER_SERIAL_AUART) += serial_auart.o
obj-$(CONFIG_DRIVER_SERIAL_CADENCE) += serial_cadence.o
obj-$(CONFIG_DRIVER_SERIAL_EFI_STDIO) += efi-stdio.o
obj-$(CONFIG_DRIVER_SERIAL_DIGIC) += serial_digic.o
+obj-$(CONFIG_DRIVER_SERIAL_LPUART) += serial_lpuart.o
diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c
new file mode 100644
index 0000000..52fb6d3
--- /dev/null
+++ b/drivers/serial/serial_lpuart.c
@@ -0,0 +1,217 @@
+/*
+ * Copyright (c) 2016 Zodiac Inflight Innovation
+ * Author: Andrey Smirnov <andrew.smirnov at gmail.com>
+ *
+ * Based on analogous driver from U-Boot
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <common.h>
+#include <driver.h>
+#include <init.h>
+#include <malloc.h>
+#include <notifier.h>
+#include <io.h>
+#include <of.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <serial/lpuart.h>
+
+struct lpuart {
+ struct console_device cdev;
+ int baudrate;
+ int dte_mode;
+ struct notifier_block notify;
+ struct resource *io;
+ void __iomem *base;
+ struct clk *clk;
+};
+
+static struct lpuart *cdev_to_lpuart(struct console_device *cdev)
+{
+ return container_of(cdev, struct lpuart, cdev);
+}
+
+static struct lpuart *nb_to_lpuart(struct notifier_block *nb)
+{
+ return container_of(nb, struct lpuart, notify);
+}
+
+static void lpuart_enable(struct lpuart *lpuart, bool on)
+{
+ u8 ctrl;
+
+ ctrl = readb(lpuart->base + UARTCR2);
+ if (on)
+ ctrl |= UARTCR2_TE | UARTCR2_RE;
+ else
+ ctrl &= ~(UARTCR2_TE | UARTCR2_RE);
+ writeb(ctrl, lpuart->base + UARTCR2);
+}
+
+static int lpuart_serial_setbaudrate(struct console_device *cdev,
+ int baudrate)
+{
+ struct lpuart *lpuart = cdev_to_lpuart(cdev);
+
+ lpuart_enable(lpuart, false);
+
+ lpuart_setbrg(lpuart->base,
+ clk_get_rate(lpuart->clk),
+ baudrate);
+
+ lpuart_enable(lpuart, true);
+
+ lpuart->baudrate = baudrate;
+
+ return 0;
+}
+
+static int lpuart_serial_getc(struct console_device *cdev)
+{
+ bool ready;
+ struct lpuart *lpuart = cdev_to_lpuart(cdev);
+
+ do {
+ const u8 sr1 = readb(lpuart->base + UARTSR1);
+ ready = !!(sr1 & (UARTSR1_OR | UARTSR1_RDRF));
+ } while (!ready);
+
+ return readb(lpuart->base + UARTDR);
+}
+
+static void lpuart_serial_putc(struct console_device *cdev, char c)
+{
+ lpuart_putc(cdev_to_lpuart(cdev)->base, c);
+}
+
+/* Test whether a character is in the RX buffer */
+static int lpuart_serial_tstc(struct console_device *cdev)
+{
+ return !!readb(cdev_to_lpuart(cdev)->base + UARTRCFIFO);
+}
+
+static void lpuart_serial_flush(struct console_device *cdev)
+{
+ bool tx_empty;
+ struct lpuart *lpuart = cdev_to_lpuart(cdev);
+
+ do {
+ const u8 sr1 = readb(lpuart->base + UARTSR1);
+ tx_empty = !!(sr1 & UARTSR1_TDRE);
+ } while (!tx_empty);
+}
+
+static int lpuart_clocksource_clock_change(struct notifier_block *nb,
+ unsigned long event, void *data)
+{
+ struct lpuart *lpuart = nb_to_lpuart(nb);
+
+ return lpuart_serial_setbaudrate(&lpuart->cdev, lpuart->baudrate);
+}
+
+static int lpuart_serial_probe(struct device_d *dev)
+{
+ int ret;
+ struct console_device *cdev;
+ struct lpuart *lpuart;
+ const char *devname;
+
+ lpuart = xzalloc(sizeof(*lpuart));
+ cdev = &lpuart->cdev;
+ dev->priv = lpuart;
+
+ lpuart->io = dev_request_mem_resource(dev, 0);
+ if (IS_ERR(lpuart->io)) {
+ ret = PTR_ERR(lpuart->io);
+ goto err_free;
+ }
+ lpuart->base = IOMEM(lpuart->io->start);
+
+ lpuart->clk = clk_get(dev, NULL);
+ if (IS_ERR(lpuart->clk)) {
+ ret = PTR_ERR(lpuart->clk);
+ dev_err(dev, "Failed to get UART clock %d\n", ret);
+ goto io_release;
+ }
+
+ ret = clk_enable(lpuart->clk);
+ if (ret) {
+ dev_err(dev, "Failed to enable UART clock %d\n", ret);
+ goto io_release;
+ }
+
+ cdev->dev = dev;
+ cdev->tstc = lpuart_serial_tstc;
+ cdev->putc = lpuart_serial_putc;
+ cdev->getc = lpuart_serial_getc;
+ cdev->flush = lpuart_serial_flush;
+ cdev->setbrg = lpuart_serial_setbaudrate;
+
+ if (dev->device_node) {
+ devname = of_alias_get(dev->device_node);
+ if (devname) {
+ cdev->devname = xstrdup(devname);
+ cdev->devid = DEVICE_ID_SINGLE;
+ }
+ }
+
+ cdev->linux_console_name = "ttyLP";
+
+ lpuart_setup_with_fifo(lpuart->base,
+ clk_get_rate(lpuart->clk),
+ 15);
+
+ ret = console_register(cdev);
+ if (!ret) {
+ lpuart->notify.notifier_call = lpuart_clocksource_clock_change;
+ clock_register_client(&lpuart->notify);
+
+ return 0;
+ }
+
+ clk_put(lpuart->clk);
+io_release:
+ release_region(lpuart->io);
+err_free:
+ free(lpuart);
+
+ return ret;
+}
+
+static void lpuart_serial_remove(struct device_d *dev)
+{
+ struct lpuart *lpuart = dev->priv;
+
+ lpuart_serial_flush(&lpuart->cdev);
+ console_unregister(&lpuart->cdev);
+ release_region(lpuart->io);
+ clk_put(lpuart->clk);
+
+ free(lpuart);
+}
+
+static struct of_device_id lpuart_serial_dt_ids[] = {
+ { .compatible = "fsl,vf610-lpuart" },
+ {}
+};
+
+static struct driver_d lpuart_serial_driver = {
+ .name = "lpuart-serial",
+ .probe = lpuart_serial_probe,
+ .remove = lpuart_serial_remove,
+ .of_compatible = DRV_OF_COMPAT(lpuart_serial_dt_ids),
+};
+console_platform_driver(lpuart_serial_driver);
diff --git a/include/serial/lpuart.h b/include/serial/lpuart.h
index 13077f9..632e976 100644
--- a/include/serial/lpuart.h
+++ b/include/serial/lpuart.h
@@ -225,25 +225,35 @@ static inline void lpuart_setbrg(void __iomem *base,
unsigned int refclock,
unsigned int baudrate)
{
+ unsigned int bfra;
u16 sbr;
+
sbr = (u16) (refclock / (16 * baudrate));
writeb(sbr >> 8, base + UARTBDH);
writeb(sbr & 0xff, base + UARTBDL);
+
+ bfra = DIV_ROUND_UP(2 * refclock, baudrate) - 32 * sbr;
+ bfra &= UARTCR4_BRFA_MASK;
+ writeb(bfra, base + UARTCR4);
}
-static inline void lpuart_setup(void __iomem *base,
- unsigned int refclock)
+static inline void lpuart_setup_with_fifo(void __iomem *base,
+ unsigned int refclock,
+ unsigned int twfifo)
{
-
/* Disable UART */
writeb(0, base + UARTCR2);
writeb(0, base + UARTMODEM);
writeb(0, base + UARTCR1);
- /* Disable FIFOs */
- writeb(0, base + UARTPFIFO);
- writeb(0, base + UARTTWFIFO);
+ if (twfifo) {
+ writeb(UARTPFIFO_TXFE | UARTPFIFO_RXFE, base + UARTPFIFO);
+ writeb((u8)twfifo, base + UARTTWFIFO);
+ } else {
+ writeb(0, base + UARTPFIFO);
+ writeb(0, base + UARTTWFIFO);
+ }
writeb(1, base + UARTRWFIFO);
writeb(UARTCFIFO_RXFLUSH | UARTCFIFO_TXFLUSH, base + UARTCFIFO);
@@ -252,6 +262,12 @@ static inline void lpuart_setup(void __iomem *base,
writeb(UARTCR2_TE | UARTCR2_RE, base + UARTCR2);
}
+static inline void lpuart_setup(void __iomem *base,
+ unsigned int refclock)
+{
+ lpuart_setup_with_fifo(base, refclock, 0x00);
+}
+
static inline void lpuart_putc(void __iomem *base, int c)
{
if (!(readb(base + UARTCR2) & UARTCR2_TE))
--
2.5.5
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