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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 3/4] xen: drivers: char: Add Device Tree Based NS16550 UART driver.
This patch adds a device tree based driver for ns16550 UART.
Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxx>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@xxxxxxxxxx>
---
xen/drivers/char/Makefile | 1 +
xen/drivers/char/ns16550-dt.c | 302 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 303 insertions(+)
create mode 100644 xen/drivers/char/ns16550-dt.c
diff --git a/xen/drivers/char/Makefile b/xen/drivers/char/Makefile
index 911b788..7c22a1b 100644
--- a/xen/drivers/char/Makefile
+++ b/xen/drivers/char/Makefile
@@ -5,4 +5,5 @@ obj-$(HAS_EXYNOS4210) += exynos4210-uart.o
obj-$(HAS_OMAP) += omap-uart.o
obj-$(HAS_EHCI) += ehci-dbgp.o
obj-$(CONFIG_ARM) += dt-uart.o
+obj-$(HAS_NS16550_DT) += ns16550-dt.o
obj-y += serial.o
diff --git a/xen/drivers/char/ns16550-dt.c b/xen/drivers/char/ns16550-dt.c
new file mode 100644
index 0000000..74d2b57
--- /dev/null
+++ b/xen/drivers/char/ns16550-dt.c
@@ -0,0 +1,302 @@
+/*
+ * xen/drivers/char/ns16550.c
+ *
+ * Driver for ns16550 UART based on DT bindigs.
+ *
+ * Pranavkumar Sawargaonkar <psawargaonkar@xxxxxxx>
+ * Anup Patel <apatel@xxxxxxx>
+ * Copyright (c) 2013 Applied Micro.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 <xen/config.h>
+#include <xen/console.h>
+#include <xen/serial.h>
+#include <xen/init.h>
+#include <xen/irq.h>
+#include <asm/early_printk.h>
+#include <xen/device_tree.h>
+#include <xen/errno.h>
+#include <asm/device.h>
+#include <xen/mm.h>
+#include <xen/vmap.h>
+#include <xen/8250-uart.h>
+
+static struct ns16550 {
+ unsigned int baud, clock_hz, data_bits, parity, stop_bits;
+ unsigned int fifo_size;
+ unsigned int reg_align; /* Regs alignement */
+ struct dt_irq irq;
+ void __iomem *regs;
+ /* UART with IRQ line: interrupt-driven I/O. */
+ struct irqaction irqaction;
+ struct vuart_info vuart;
+} ns16550_com = {0};
+
+
+static char ns16550_read(struct ns16550 *uart, int reg)
+{
+ return ioreadl((uart)->regs + (reg * (uart->reg_align)));
+}
+
+static void ns16550_write(struct ns16550 *uart, int reg, char c)
+{
+ iowritel((uart)->regs + (reg * (uart->reg_align)), c);
+}
+
+static void ns16550_interrupt(int irq, void *data, struct cpu_user_regs *regs)
+{
+ struct serial_port *port = data;
+ struct ns16550 *uart = port->uart;
+
+ while ( !(ns16550_read(uart, UART_IIR) & UART_IIR_NOINT) )
+ {
+ char lsr = ns16550_read(uart, UART_LSR);
+ if ( lsr & UART_LSR_THRE )
+ serial_tx_interrupt(port, regs);
+ if ( lsr & UART_LSR_DR )
+ serial_rx_interrupt(port, regs);
+ }
+}
+
+static void ns16550_setup_preirq(struct ns16550 *uart)
+{
+ unsigned char lcr;
+ unsigned int divisor;
+
+ lcr = (uart->data_bits - 5) | ((uart->stop_bits - 1) << 2) | uart->parity;
+
+ /* No interrupts. */
+ ns16550_write(uart, UART_IER, 0);
+
+ /* Line control and baud-rate generator. */
+ ns16550_write(uart, UART_LCR, lcr | UART_LCR_DLAB);
+ if ( uart->baud != BAUD_AUTO )
+ {
+ /* Baud rate specified: program it into the divisor latch. */
+ divisor = uart->clock_hz / (uart->baud << 4);
+ ns16550_write(uart, UART_DLL, (char)divisor);
+ ns16550_write(uart, UART_DLM, (char)(divisor >> 8));
+ }
+ else
+ {
+ /* Baud rate already set: read it out from the divisor latch. */
+ divisor = ns16550_read(uart, UART_DLL);
+ divisor |= ns16550_read(uart, UART_DLM) << 8;
+ uart->baud = uart->clock_hz / (divisor << 4);
+ }
+ ns16550_write(uart, UART_LCR, lcr);
+
+ /* No flow ctrl: DTR and RTS are both wedged high to keep remote happy. */
+ ns16550_write(uart, UART_MCR, UART_MCR_DTR | UART_MCR_RTS);
+
+ /* Enable and clear the FIFOs. Set a large trigger threshold. */
+ ns16550_write(uart, UART_FCR,
+ UART_FCR_ENABLE | UART_FCR_CLRX | UART_FCR_CLTX |
UART_FCR_TRG14);
+}
+
+static void __init ns16550_init_preirq(struct serial_port *port)
+{
+ struct ns16550 *uart = port->uart;
+
+ ns16550_setup_preirq(uart);
+
+ /* Check this really is a 16550+. Otherwise we have no FIFOs. */
+ if ( ((ns16550_read(uart, UART_IIR) & 0xc0) == 0xc0) &&
+ ((ns16550_read(uart, UART_FCR) & UART_FCR_TRG14) == UART_FCR_TRG14) )
+ uart->fifo_size = 16;
+}
+
+static void ns16550_setup_postirq(struct ns16550 *uart)
+{
+ if ( uart->irq.irq > 0 )
+ {
+ /* Master interrupt enable; also keep DTR/RTS asserted. */
+ ns16550_write(uart,
+ UART_MCR, UART_MCR_OUT2 | UART_MCR_DTR | UART_MCR_RTS);
+
+ /* Enable receive and transmit interrupts. */
+ ns16550_write(uart, UART_IER, UART_IER_ERDAI | UART_IER_ETHREI);
+ }
+}
+
+static void __init ns16550_init_postirq(struct serial_port *port)
+{
+ struct ns16550 *uart = port->uart;
+ int rc, bits;
+
+ if ( uart->irq.irq < 0 )
+ return;
+
+ /* Calculate time to fill RX FIFO and/or empty TX FIFO for polling. */
+ bits = uart->data_bits + uart->stop_bits + !!uart->parity;
+
+ if ( uart->irq.irq > 0 )
+ {
+ uart->irqaction.handler = ns16550_interrupt;
+ uart->irqaction.name = "ns16550";
+ uart->irqaction.dev_id = port;
+ if ( (rc = setup_dt_irq(&uart->irq, &uart->irqaction)) != 0 )
+ printk("ERROR: Failed to allocate ns16550 IRQ %d\n",
uart->irq.irq);
+ }
+
+ ns16550_setup_postirq(uart);
+}
+
+static int ns16550_tx_ready(struct serial_port *port)
+{
+ struct ns16550 *uart = port->uart;
+
+ return ns16550_read(uart, UART_LSR) & UART_LSR_THRE ? uart->fifo_size : 0;
+}
+
+static void ns16550_putc(struct serial_port *port, char c)
+{
+ struct ns16550 *uart = port->uart;
+
+ ns16550_write(uart, UART_THR, c);
+}
+
+static int ns16550_getc(struct serial_port *port, char *pc)
+{
+ struct ns16550 *uart = port->uart;
+
+ if ( !(ns16550_read(uart, UART_LSR) & UART_LSR_DR) )
+ return 0;
+
+ *pc = ns16550_read(uart, UART_RBR);
+ return 1;
+}
+
+static void ns16550_suspend(struct serial_port *port)
+{
+ BUG(); // XXX
+}
+
+static void ns16550_resume(struct serial_port *port)
+{
+ BUG(); // XXX
+}
+
+static int __init ns16550_irq(struct serial_port *port)
+{
+ struct ns16550 *uart = port->uart;
+ return ((uart->irq.irq > 0) ? uart->irq.irq : -1);
+}
+
+static const struct dt_irq __init *ns16550_dt_irq(struct serial_port *port)
+{
+ struct ns16550 *uart = port->uart;
+
+ return &uart->irq;
+}
+
+static const struct vuart_info *ns16550_vuart(struct serial_port *port)
+{
+ struct ns16550 *uart = port->uart;
+
+ return &uart->vuart;
+}
+
+static struct uart_driver __read_mostly ns16550_driver = {
+ .init_preirq = ns16550_init_preirq,
+ .init_postirq = ns16550_init_postirq,
+ .endboot = NULL,
+ .suspend = ns16550_suspend,
+ .resume = ns16550_resume,
+ .tx_ready = ns16550_tx_ready,
+ .putc = ns16550_putc,
+ .getc = ns16550_getc,
+ .irq = ns16550_irq,
+ .dt_irq_get = ns16550_dt_irq,
+ .vuart_info = ns16550_vuart,
+};
+
+/* TODO: Parse UART config from the command line */
+static int __init ns16550_uart_init(struct dt_device_node *dev,
+ const void *data)
+{
+ const char *config = data;
+ struct ns16550 *uart;
+ int res;
+ u64 addr, size;
+
+ if ( strcmp(config, "") )
+ {
+ early_printk("WARNING: UART configuration is not supported\n");
+ }
+
+ uart = &ns16550_com;
+
+ uart->clock_hz = 50000000;
+ uart->baud = 115200;
+ uart->data_bits = 8;
+ uart->parity = UART_PARITY_NONE; /* FIXME */
+ uart->stop_bits = 1;
+ uart->reg_align = 4;
+
+ res = dt_device_get_address(dev, 0, &addr, &size);
+ if ( res )
+ {
+ early_printk("ns16550: Unable to retrieve the base"
+ " address of the UART\n");
+ return res;
+ }
+
+ uart->regs = ioremap_attr(addr, size, PAGE_HYPERVISOR_NOCACHE);
+ if ( !uart->regs )
+ {
+ early_printk("ns16550: Unable to map the UART memory\n");
+
+ return -ENOMEM;
+ }
+
+ res = dt_device_get_irq(dev, 0, &uart->irq);
+ if ( res )
+ {
+ early_printk("ns16550: Unable to retrieve the IRQ\n");
+ return res;
+ }
+
+ uart->vuart.base_addr = addr;
+ uart->vuart.size = size;
+ uart->vuart.data_off = (UART_THR * uart->reg_align) ;
+ uart->vuart.status_off = (UART_LSR * uart->reg_align);
+ uart->vuart.status = UART_LSR_THRE;
+
+ /* Register with generic serial driver. */
+ serial_register_uart(SERHND_DTUART, &ns16550_driver, uart);
+
+ dt_device_set_used_by(dev, DOMID_XEN);
+
+ return 0;
+}
+
+static const char const *ns16550_dt_compat[] __initdata =
+{
+ "ns16550",
+ NULL
+};
+
+DT_DEVICE_START(ns16550, "NS16550 UART", DEVICE_SERIAL)
+ .compatible = ns16550_dt_compat,
+ .init = ns16550_uart_init,
+DT_DEVICE_END
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
--
1.8.2.1
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