[U-Boot] [PATCH v1 01/16] serial: Add support for Qualcomm serial port

Mateusz Kulikowski
2016-01-06T18:21:13Z

This driver works in "new" Data Mover UART mode, so
will be compatible with modern Qualcomm chips only.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
---

Changes in v1:
- Added (better) help to KConfig
- Added dt binding documentation
- Fixed include ordering
- Reworked msm_serial_getc
- Added error handling to msm_uart_clk_init (that is ignored later for now)
- Dropped unneeded DM_FLAG_PRE_RELOC

doc/device-tree-bindings/serial/msm-serial.txt | 6 +
drivers/serial/Kconfig | 8 +
drivers/serial/Makefile | 1 +
drivers/serial/serial_msm.c | 206 +++++++++++++++++++++++++
4 files changed, 221 insertions(+)
create mode 100644 doc/device-tree-bindings/serial/msm-serial.txt
create mode 100644 drivers/serial/serial_msm.c

diff --git a/doc/device-tree-bindings/serial/msm-serial.txt b/doc/device-tree-bindings/serial/msm-serial.txt
new file mode 100644
index 0000000..48b8428
--- /dev/null
+++ b/doc/device-tree-bindings/serial/msm-serial.txt
@@ -0,0 +1,6 @@
+Qualcomm UART (Data Mover mode)
+
+Required properties:
+- compatible: must be "qcom,msm-uartdm-v1.4"
+- reg: start address and size of the registers
+- clock: interface clock (must accept baudrate as a frequency)
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 1fc287e..56d7b76 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -223,4 +223,12 @@ config UNIPHIER_SERIAL
If you have a UniPhier based board and want to use the on-chip
serial ports, say Y to this option. If unsure, say N.

+config MSM_SERIAL
+ bool "Qualcomm on-chip UART"
+ depends on DM_SERIAL
+ help
+ Support Data Mover UART used on Qualcomm Snapdragon SoCs.
+ It should support all Qualcomm devices with UARTDM version 1.4,
+ for example APQ8016 and MSM8916.
+ Single baudrate is supported in current implementation (115200).
endmenu
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index dd87147..d052175 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_MXS_AUART) += mxs_auart.o
obj-$(CONFIG_ARC_SERIAL) += serial_arc.o
obj-$(CONFIG_UNIPHIER_SERIAL) += serial_uniphier.o
obj-$(CONFIG_STM32_SERIAL) += serial_stm32.o
+obj-$(CONFIG_MSM_SERIAL) += serial_msm.o

ifndef CONFIG_SPL_BUILD
obj-$(CONFIG_USB_TTY) += usbtty.o
diff --git a/drivers/serial/serial_msm.c b/drivers/serial/serial_msm.c
new file mode 100644
index 0000000..344f254
--- /dev/null
+++ b/drivers/serial/serial_msm.c
@@ -0,0 +1,206 @@
+/*
+ * Qualcomm UART driver
+ *
+ * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
+ *
+ * UART will work in Data Mover mode.
+ * Based on Linux driver.
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <errno.h>
+#include <serial.h>
+#include <watchdog.h>
+#include <asm/io.h>
+#include <linux/compiler.h>
+
+/* Serial registers - this driver works in uartdm mode*/
+
+#define UARTDM_DMRX 0x34 /* Max RX transfer length */
+#define UARTDM_NCF_TX 0x40 /* Number of chars to TX */
+
+#define UARTDM_RXFS 0x50 /* RX channel status register */
+#define UARTDM_RXFS_BUF_SHIFT 0x7 /* Number of bytes in the packing buffer */
+#define UARTDM_RXFS_BUF_MASK 0x7
+
+#define UARTDM_SR 0xA4 /* Status register */
+#define UARTDM_SR_RX_READY (1 << 0) /* Word is the receiver FIFO */
+#define UARTDM_SR_TX_EMPTY (1 << 3) /* Transmitter underrun */
+#define UARTDM_SR_UART_OVERRUN (1 << 4) /* Receive overrun */
+
+#define UARTDM_CR 0xA8 /* Command register */
+#define UARTDM_CR_CMD_RESET_ERR (3 << 4) /* Clear overrun error */
+#define UARTDM_CR_CMD_RESET_STALE_INT (8 << 4) /* Clears stale irq */
+#define UARTDM_CR_CMD_RESET_TX_READY (3 << 8) /* Clears TX Ready irq*/
+#define UARTDM_CR_CMD_FORCE_STALE (4 << 8) /* Causes stale event */
+#define UARTDM_CR_CMD_STALE_EVENT_DISABLE (6 << 8) /* Disable stale event */
+
+#define UARTDM_IMR 0xB0 /* Interrupt mask register */
+#define UARTDM_ISR 0xB4 /* Interrupt status register */
+#define UARTDM_ISR_TX_READY 0x80 /* TX FIFO empty */
+
+#define UARTDM_TF 0x100 /* UART Transmit FIFO register */
+#define UARTDM_RF 0x140 /* UART Receive FIFO register */
+
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct msm_serial_data {
+ phys_addr_t base;
+ unsigned chars_cnt; /* number of buffered chars */
+ uint32_t chars_buf; /* buffered chars */
+};
+
+static int msm_serial_getc(struct udevice *dev)
+{
+ struct msm_serial_data *p = dev_get_priv(dev);
+ char c;
+ unsigned sr;
+
+ if (!p->chars_buf) {
+ /* Clear error in case of buffer overrun */
+ if (readl(p->base + UARTDM_SR) & UARTDM_SR_UART_OVERRUN)
+ writel(UARTDM_CR_CMD_RESET_ERR, p->base + UARTDM_CR);
+
+ /* We need to fetch new character */
+ sr = readl(p->base + UARTDM_SR);
+
+ if (sr & UARTDM_SR_RX_READY) {
+ /* There are at least 4 bytes in fifo */
+ p->chars_buf = readl(p->base + UARTDM_RF);
+ p->chars_cnt = 4;
+ } else {
+ /* Check if there is anything in fifo */
+ p->chars_cnt = readl(p->base + UARTDM_RXFS);
+ /* Extract number of characters in UART packing buffer*/
+ p->chars_cnt = (p->chars_cnt >> UARTDM_RXFS_BUF_SHIFT) &
+ UARTDM_RXFS_BUF_MASK;
+ if (!p->chars_cnt)
+ return -EAGAIN;
+
+ /* There is at least one charcter, move it to fifo */
+ writel(UARTDM_CR_CMD_FORCE_STALE, p->base + UARTDM_CR);
+
+ p->chars_buf = readl(p->base + UARTDM_RF);
+ writel(UARTDM_CR_CMD_RESET_STALE_INT,
+ p->base + UARTDM_CR);
+ writel(0xFFFFFF, p->base + UARTDM_DMRX);
+ }
+ }
+
+ c = p->chars_buf & 0xFF;
+ p->chars_buf >>= 8;
+ p->chars_cnt--;
+
+ return c;
+}
+
+static int msm_serial_putc(struct udevice *dev, const char ch)
+{
+ struct msm_serial_data *p = dev_get_priv(dev);
+
+ if (!(readl(p->base + UARTDM_SR) & UARTDM_SR_TX_EMPTY) &&
+ !(readl(p->base + UARTDM_ISR) & UARTDM_ISR_TX_READY))
+ return -EAGAIN;
+
+ writel(UARTDM_CR_CMD_RESET_TX_READY, p->base + UARTDM_CR);
+
+ writel(1, p->base + UARTDM_NCF_TX);
+ writel(ch, p->base + UARTDM_TF);
+ return 0;
+}
+
+static int msm_serial_pending(struct udevice *dev, bool input)
+{
+ struct msm_serial_data *p = dev_get_priv(dev);
+
+ if (input) {
+ if (p->chars_cnt)
+ return 1;
+ if (readl(p->base + UARTDM_SR) & UARTDM_SR_RX_READY)
+ return 1;
+ if (readl(p->base + UARTDM_RXFS))
+ return 1;
+ }
+ return 0;
+}
+
+static const struct dm_serial_ops msm_serial_ops = {
+ .putc = msm_serial_putc,
+ .pending = msm_serial_pending,
+ .getc = msm_serial_getc,
+};
+
+static int msm_uart_clk_init(struct udevice *dev)
+{
+ uint clk_rate = fdtdec_get_uint(gd->fdt_blob, dev->of_offset,
+ "clock-frequency", 115200);
+ uint clkd[2]; /* clk_id and clk_no */
+ int clk_offset;
+ struct udevice *clk;
+ int ret;
+
+ ret = fdtdec_get_int_array(gd->fdt_blob, dev->of_offset, "clock", clkd,
+ 2);
+ if (ret)
+ return ret;
+
+ clk_offset = fdt_node_offset_by_phandle(gd->fdt_blob, clkd[0]);
+ if (clk_offset < 0)
+ return clk_offset;
+
+ ret = uclass_get_device_by_of_offset(UCLASS_CLK, clk_offset, &clk);
+ if (ret)
+ return ret;
+
+ ret = clk_set_periph_rate(clk, clkd[1], clk_rate);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+static int msm_serial_probe(struct udevice *dev)
+{
+ struct msm_serial_data *p = dev_get_priv(dev);
+
+ msm_uart_clk_init(dev); /* Ignore return value and hope clock was
+ properly initialized by earlier loaders */
+
+ if (readl(p->base + UARTDM_SR) & UARTDM_SR_UART_OVERRUN)
+ writel(UARTDM_CR_CMD_RESET_ERR, p->base + UARTDM_CR);
+
+ writel(0, p->base + UARTDM_IMR);
+ writel(UARTDM_CR_CMD_STALE_EVENT_DISABLE, p->base + UARTDM_CR);
+ writel(0xFFFFFF, p->base + UARTDM_DMRX);
+ return 0;
+}
+
+static int msm_serial_ofdata_to_platdata(struct udevice *dev)
+{
+ struct msm_serial_data *p = dev_get_priv(dev);
+
+ p->base = dev_get_addr(dev);
+ if (p->base == FDT_ADDR_T_NONE)
+ return -EINVAL;
+ return 0;
+}
+
+static const struct udevice_id msm_serial_ids[] = {
+ { .compatible = "qcom,msm-uartdm-v1.4" },
+ { }
+};
+
+U_BOOT_DRIVER(serial_msm) = {
+ .name = "serial_msm",
+ .id = UCLASS_SERIAL,
+ .of_match = msm_serial_ids,
+ .ofdata_to_platdata = msm_serial_ofdata_to_platdata,
+ .priv_auto_alloc_size = sizeof(struct msm_serial_data),
+ .probe = msm_serial_probe,
+ .ops = &msm_serial_ops,
+};
--
2.5.0