diff options
Diffstat (limited to 'drivers/tty/serial/8250_dw.c')
| -rw-r--r-- | drivers/tty/serial/8250_dw.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250_dw.c b/drivers/tty/serial/8250_dw.c new file mode 100644 index 000000000000..bf1fba640c2d --- /dev/null +++ b/drivers/tty/serial/8250_dw.c @@ -0,0 +1,194 @@ +/* + * Synopsys DesignWare 8250 driver. + * + * Copyright 2011 Picochip, Jamie Iles. + * + * 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. + * + * The Synopsys DesignWare 8250 has an extra feature whereby it detects if the + * LCR is written whilst busy. If it is, then a busy detect interrupt is + * raised, the LCR needs to be rewritten and the uart status register read. + */ +#include <linux/device.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/serial_8250.h> +#include <linux/serial_core.h> +#include <linux/serial_reg.h> +#include <linux/of.h> +#include <linux/of_irq.h> +#include <linux/of_platform.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +struct dw8250_data { + int last_lcr; + int line; +}; + +static void dw8250_serial_out(struct uart_port *p, int offset, int value) +{ + struct dw8250_data *d = p->private_data; + + if (offset == UART_LCR) + d->last_lcr = value; + + offset <<= p->regshift; + writeb(value, p->membase + offset); +} + +static unsigned int dw8250_serial_in(struct uart_port *p, int offset) +{ + offset <<= p->regshift; + + return readb(p->membase + offset); +} + +static void dw8250_serial_out32(struct uart_port *p, int offset, int value) +{ + struct dw8250_data *d = p->private_data; + + if (offset == UART_LCR) + d->last_lcr = value; + + offset <<= p->regshift; + writel(value, p->membase + offset); +} + +static unsigned int dw8250_serial_in32(struct uart_port *p, int offset) +{ + offset <<= p->regshift; + + return readl(p->membase + offset); +} + +/* Offset for the DesignWare's UART Status Register. */ +#define UART_USR 0x1f + +static int dw8250_handle_irq(struct uart_port *p) +{ + struct dw8250_data *d = p->private_data; + unsigned int iir = p->serial_in(p, UART_IIR); + + if (serial8250_handle_irq(p, iir)) { + return 1; + } else if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) { + /* Clear the USR and write the LCR again. */ + (void)p->serial_in(p, UART_USR); + p->serial_out(p, d->last_lcr, UART_LCR); + + return 1; + } + + return 0; +} + +static int __devinit dw8250_probe(struct platform_device *pdev) +{ + struct uart_port port = {}; + struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0); + struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); + struct device_node *np = pdev->dev.of_node; + u32 val; + struct dw8250_data *data; + + if (!regs || !irq) { + dev_err(&pdev->dev, "no registers/irq defined\n"); + return -EINVAL; + } + + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + port.private_data = data; + + spin_lock_init(&port.lock); + port.mapbase = regs->start; + port.irq = irq->start; + port.handle_irq = dw8250_handle_irq; + port.type = PORT_8250; + port.flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP | + UPF_FIXED_PORT | UPF_FIXED_TYPE; + port.dev = &pdev->dev; + + port.iotype = UPIO_MEM; + port.serial_in = dw8250_serial_in; + port.serial_out = dw8250_serial_out; + if (!of_property_read_u32(np, "reg-io-width", &val)) { + switch (val) { + case 1: + break; + case 4: + port.iotype = UPIO_MEM32; + port.serial_in = dw8250_serial_in32; + port.serial_out = dw8250_serial_out32; + break; + default: + dev_err(&pdev->dev, "unsupported reg-io-width (%u)\n", + val); + return -EINVAL; + } + } + + if (!of_property_read_u32(np, "reg-shift", &val)) + port.regshift = val; + + if (of_property_read_u32(np, "clock-frequency", &val)) { + dev_err(&pdev->dev, "no clock-frequency property set\n"); + return -EINVAL; + } + port.uartclk = val; + + data->line = serial8250_register_port(&port); + if (data->line < 0) + return data->line; + + platform_set_drvdata(pdev, data); + + return 0; +} + +static int __devexit dw8250_remove(struct platform_device *pdev) +{ + struct dw8250_data *data = platform_get_drvdata(pdev); + + serial8250_unregister_port(data->line); + + return 0; +} + +static const struct of_device_id dw8250_match[] = { + { .compatible = "snps,dw-apb-uart" }, + { /* Sentinel */ } +}; +MODULE_DEVICE_TABLE(of, dw8250_match); + +static struct platform_driver dw8250_platform_driver = { + .driver = { + .name = "dw-apb-uart", + .owner = THIS_MODULE, + .of_match_table = dw8250_match, + }, + .probe = dw8250_probe, + .remove = __devexit_p(dw8250_remove), +}; + +static int __init dw8250_init(void) +{ + return platform_driver_register(&dw8250_platform_driver); +} +module_init(dw8250_init); + +static void __exit dw8250_exit(void) +{ + platform_driver_unregister(&dw8250_platform_driver); +} +module_exit(dw8250_exit); + +MODULE_AUTHOR("Jamie Iles"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Synopsys DesignWare 8250 serial port driver"); |