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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 3/4] xen: drivers: char: Add Device Tree Based NS16550 UART driver.
On Fri, 2013-09-20 at 15:22 +0530, Pranavkumar Sawargaonkar wrote:
> This patch adds a device tree based driver for ns16550 UART.
I posted patches last week (or the week before) to support the
cubieboard2 and that series included a patch to enable the existing
ns16550 driver to be used on DT as well. I think that is better than
duplicating the majority of the driver just differ in a few probe
routines.
Does that approach work for you?
>
> 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:
> + */
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