[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 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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