[Xen-devel] [PATCH v3 1/2] xen/arm: Add MVEBU UART driver for Marvell Armada 3700 SoC

[Amit Singh Tomar <amittomer25@xxxxxxxxx>]

This patch adds driver for UART controller found on Armada 3700 SoC.

There is no reference manuals available for 3700 SoC in public and it
is derived by looking at Linux driver[1].

[1]https://github.com/torvalds/linux/blob/master/drivers/tty/serial/mvebu-uart.c

Signed-off-by: Amit Singh Tomar <amittomer25@xxxxxxxxx>
---
Changes since v2:
    * Addressed Andre's comments.
Changes since v1:
    * Addressed Wei Liu's comments
    * Addressed Andre's comments.
Changes since RFC:
    * Addressed Julien's comments.
---
 xen/drivers/char/Kconfig      |   8 ++
 xen/drivers/char/Makefile     |   1 +
 xen/drivers/char/mvebu-uart.c | 296 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 305 insertions(+)
 create mode 100644 xen/drivers/char/mvebu-uart.c

diff --git a/xen/drivers/char/Kconfig b/xen/drivers/char/Kconfig
index fb53dd8..04a4087 100644
--- a/xen/drivers/char/Kconfig
+++ b/xen/drivers/char/Kconfig
@@ -12,6 +12,14 @@ config HAS_CADENCE_UART
          This selects the Xilinx Zynq Cadence UART. If you have a Xilinx Zynq
          based board, say Y.

+config HAS_MVEBU
+    bool
+    default y
+    depends on ARM_64
+    help
+      This selects the Marvell MVEBU UART. If you have a ARMADA 3700
+      based board, say Y.
+
 config HAS_PL011
        bool
        default y
diff --git a/xen/drivers/char/Makefile b/xen/drivers/char/Makefile
index 0d48b16..b68c330 100644
--- a/xen/drivers/char/Makefile
+++ b/xen/drivers/char/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_HAS_NS16550) += ns16550.o
 obj-$(CONFIG_HAS_CADENCE_UART) += cadence-uart.o
 obj-$(CONFIG_HAS_PL011) += pl011.o
 obj-$(CONFIG_HAS_EXYNOS4210) += exynos4210-uart.o
+obj-$(CONFIG_HAS_MVEBU) += mvebu-uart.o
 obj-$(CONFIG_HAS_OMAP) += omap-uart.o
 obj-$(CONFIG_HAS_SCIF) += scif-uart.o
 obj-$(CONFIG_HAS_EHCI) += ehci-dbgp.o
diff --git a/xen/drivers/char/mvebu-uart.c b/xen/drivers/char/mvebu-uart.c
new file mode 100644
index 0000000..1561a50
--- /dev/null
+++ b/xen/drivers/char/mvebu-uart.c
@@ -0,0 +1,296 @@
+/*
+ * xen/drivers/char/mvebu3700-uart.c
+ *
+ * Driver for Marvell MVEBU UART.
+ *
+ * Copyright (c) 2018, Amit Singh Tomar <amittomer25@xxxxxxxxx>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms and conditions 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.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <xen/irq.h>
+#include <xen/serial.h>
+#include <xen/vmap.h>
+#include <asm/io.h>
+
+/* Register offsets */
+#define UART_RX_REG             0x00
+
+#define UART_TX_REG             0x04
+
+#define UART_CTRL_REG           0x08
+#define CTRL_TXFIFO_RST         BIT(15)
+#define CTRL_RXFIFO_RST         BIT(14)
+#define CTRL_TX_RDY_INT         BIT(5)
+#define CTRL_RX_RDY_INT         BIT(4)
+#define CTRL_BRK_DET_INT        BIT(3)
+#define CTRL_FRM_ERR_INT        BIT(2)
+#define CTRL_PAR_ERR_INT        BIT(1)
+#define CTRL_OVR_ERR_INT        BIT(0)
+#define CTRL_ERR_INT            (CTRL_BRK_DET_INT | CTRL_FRM_ERR_INT | \
+                                 CTRL_PAR_ERR_INT | CTRL_OVR_ERR_INT)
+
+#define UART_STATUS_REG         0x0c
+#define STATUS_TXFIFO_EMP       BIT(13)
+#define STAT_TX_FIFO_FUL        BIT(11)
+#define STAT_TX_FIFO_HFL        BIT(10)
+#define STATUS_TX_RDY           BIT(5)
+#define STATUS_RX_RDY           BIT(4)
+#define STATUS_BRK_DET          BIT(3)
+#define STATUS_FRM_ERR          BIT(2)
+#define STATUS_PAR_ERR          BIT(1)
+#define STATUS_OVR_ERR          BIT(0)
+#define STATUS_BRK_ERR          (STATUS_BRK_DET | STATUS_FRM_ERR | \
+                                 STATUS_PAR_ERR | STATUS_OVR_ERR)
+
+#define TX_FIFO_SIZE            32
+
+static struct mvebu3700_uart {
+    unsigned int irq;
+    void __iomem *regs;
+    struct irqaction irqaction;
+    struct vuart_info vuart;
+} mvebu3700_com = {0};
+
+#define mvebu3700_read(uart, off)           readl((uart)->regs + off)
+#define mvebu3700_write(uart, off, val)     writel(val, (uart->regs) + off)
+
+static void mvebu3700_uart_interrupt(int irq, void *data,
+                                     struct cpu_user_regs *regs)
+{
+    struct serial_port *port = data;
+    struct mvebu3700_uart *uart = port->uart;
+    uint32_t st = mvebu3700_read(uart, UART_STATUS_REG);
+
+    if ( st & (STATUS_RX_RDY | STATUS_OVR_ERR | STATUS_FRM_ERR |
+               STATUS_BRK_DET) )
+        serial_rx_interrupt(port, regs);
+
+    if ( st & STATUS_TX_RDY )
+        serial_tx_interrupt(port, regs);
+}
+
+static void __init mvebu3700_uart_init_preirq(struct serial_port *port)
+{
+    struct mvebu3700_uart *uart = port->uart;
+    uint32_t reg;
+
+    reg = mvebu3700_read(uart, UART_CTRL_REG);
+    reg |= (CTRL_TXFIFO_RST | CTRL_RXFIFO_RST);
+    mvebu3700_write(uart, UART_CTRL_REG, reg);
+
+    /* Before we make IRQ request, clear the error bits of state register. */
+    reg = mvebu3700_read(uart, UART_STATUS_REG);
+    reg |= STATUS_BRK_ERR;
+    mvebu3700_write(uart, UART_STATUS_REG, reg);
+
+    /* Clear error interrupts. */
+    mvebu3700_write(uart, UART_CTRL_REG, CTRL_ERR_INT);
+
+    /* Disable Rx/Tx interrupts. */
+    reg = mvebu3700_read(uart, UART_CTRL_REG);
+    reg &= ~(CTRL_RX_RDY_INT | CTRL_TX_RDY_INT);
+    mvebu3700_write(uart, UART_CTRL_REG, reg);
+}
+
+static void __init mvebu3700_uart_init_postirq(struct serial_port *port)
+{
+    struct mvebu3700_uart *uart = port->uart;
+    uint32_t reg;
+
+    if ( uart->irq > 0 )
+    {
+        uart->irqaction.handler = mvebu3700_uart_interrupt;
+        uart->irqaction.name    = "mvebu3700_uart";
+        uart->irqaction.dev_id  = port;
+    }
+
+    if ( setup_irq(uart->irq, 0, &uart->irqaction) != 0 )
+    {
+        printk("Failed to allocated mvebu3700_uart IRQ %d\n", uart->irq);
+        return;
+    }
+
+    /* Make sure Rx/Tx interrupts are enabled now */
+    reg = mvebu3700_read(uart, UART_CTRL_REG);
+    reg |= (CTRL_RX_RDY_INT | CTRL_TX_RDY_INT);
+    mvebu3700_write(uart, UART_CTRL_REG, reg);
+}
+
+static void mvebu3700_uart_suspend(struct serial_port *port)
+{
+    BUG();
+}
+
+static void mvebu3700_uart_resume(struct serial_port *port)
+{
+    BUG();
+}
+
+static void mvebu3700_uart_putc(struct serial_port *port, char c)
+{
+    struct mvebu3700_uart *uart = port->uart;
+
+    mvebu3700_write(uart, UART_TX_REG, c);
+}
+
+static int mvebu3700_uart_getc(struct serial_port *port, char *c)
+{
+    struct mvebu3700_uart *uart = port->uart;
+
+    if ( !(mvebu3700_read(uart, UART_STATUS_REG) & STATUS_RX_RDY) )
+        return 0;
+
+    *c = mvebu3700_read(uart, UART_RX_REG) & 0xff;
+
+    return 1;
+}
+
+static int __init mvebu3700_irq(struct serial_port *port)
+{
+    struct mvebu3700_uart *uart = port->uart;
+
+    return (uart->irq > 0) ? uart->irq : -1;
+}
+
+static const struct vuart_info *mvebu3700_vuart_info(struct serial_port *port)
+{
+    struct mvebu3700_uart *uart = port->uart;
+
+    return &uart->vuart;
+}
+
+static void mvebu3700_uart_stop_tx(struct serial_port *port)
+{
+    struct mvebu3700_uart *uart = port->uart;
+    uint32_t reg;
+
+    reg = mvebu3700_read(uart, UART_CTRL_REG);
+    reg &= ~CTRL_TX_RDY_INT;
+    mvebu3700_write(uart, UART_CTRL_REG, reg);
+}
+
+static void mvebu3700_uart_start_tx(struct serial_port *port)
+{
+    struct mvebu3700_uart *uart = port->uart;
+    uint32_t reg;
+
+    reg = mvebu3700_read(uart, UART_CTRL_REG);
+    reg |= CTRL_TX_RDY_INT;
+    mvebu3700_write(uart, UART_CTRL_REG, reg);
+}
+
+static int mvebu3700_uart_tx_ready(struct serial_port *port)
+{
+    struct mvebu3700_uart *uart = port->uart;
+    uint32_t reg;
+
+    reg = mvebu3700_read(uart, UART_STATUS_REG);
+
+    if ( reg & STATUS_TXFIFO_EMP )
+        return TX_FIFO_SIZE;
+    if ( reg & STAT_TX_FIFO_FUL )
+        return 0;
+    if ( reg & STAT_TX_FIFO_HFL )
+        return TX_FIFO_SIZE / 2;
+
+    /* if we reach here, we don't know the number of free char in FIFO
+     * but we are sure that neither the FIFO is full nor empty.
+     * So, let's just return at least 1.
+     */
+    return 1;
+}
+
+static struct uart_driver __read_mostly mvebu3700_uart_driver = {
+    .init_preirq  = mvebu3700_uart_init_preirq,
+    .init_postirq = mvebu3700_uart_init_postirq,
+    .endboot      = NULL,
+    .suspend      = mvebu3700_uart_suspend,
+    .resume       = mvebu3700_uart_resume,
+    .putc         = mvebu3700_uart_putc,
+    .getc         = mvebu3700_uart_getc,
+    .tx_ready     = mvebu3700_uart_tx_ready,
+    .stop_tx      = mvebu3700_uart_stop_tx,
+    .start_tx     = mvebu3700_uart_start_tx,
+    .irq          = mvebu3700_irq,
+    .vuart_info   = mvebu3700_vuart_info,
+};
+
+static int __init mvebu_uart_init(struct dt_device_node *dev, const void *data)
+{
+    const char *config = data;
+    struct mvebu3700_uart *uart;
+    int res;
+    u64 addr, size;
+
+    if ( strcmp(config, "") )
+        printk("WARNING: UART configuration is not supported\n");
+
+    uart = &mvebu3700_com;
+
+    res = dt_device_get_address(dev, 0, &addr, &size);
+    if ( res )
+    {
+        printk("mvebu3700: Unable to retrieve the base address of the UART\n");
+        return res;
+    }
+
+    res = platform_get_irq(dev, 0);
+    if ( res < 0 )
+    {
+        printk("mvebu3700: Unable to retrieve the IRQ\n");
+        return -EINVAL;
+    }
+
+    uart->irq  = res;
+
+    uart->regs = ioremap_nocache(addr, size);
+    if ( !uart->regs )
+    {
+        printk("mvebu3700: Unable to map the UART memory\n");
+        return -ENOMEM;
+    }
+
+    uart->vuart.base_addr = addr;
+    uart->vuart.size = size;
+    uart->vuart.data_off = UART_CTRL_REG;
+    uart->vuart.status_off = UART_STATUS_REG;
+    uart->vuart.status = STATUS_TX_RDY | STATUS_RX_RDY;
+
+    /* Register with generic serial driver. */
+    serial_register_uart(SERHND_DTUART, &mvebu3700_uart_driver, uart);
+
+    dt_device_set_used_by(dev, DOMID_XEN);
+
+    return 0;
+}
+
+static const struct dt_device_match mvebu_dt_match[] __initconst =
+{
+    DT_MATCH_COMPATIBLE("marvell,armada-3700-uart"),
+    { /* sentinel */ },
+};
+
+DT_DEVICE_START(mvebu, "Marvell Armada-3700 UART", DEVICE_SERIAL)
+    .dt_match = mvebu_dt_match,
+    .init = mvebu_uart_init,
+DT_DEVICE_END
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
--
1.9.1


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