diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_bcm2835aux.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_bcm2835aux.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_bcm2835aux.c b/drivers/tty/serial/8250/8250_bcm2835aux.c new file mode 100644 index 000000000..e10f12444 --- /dev/null +++ b/drivers/tty/serial/8250/8250_bcm2835aux.c @@ -0,0 +1,146 @@ +/* + * Serial port driver for BCM2835AUX UART + * + * Copyright (C) 2016 Martin Sperl <kernel@martin.sperl.org> + * + * Based on 8250_lpc18xx.c: + * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include <linux/clk.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> + +#include "8250.h" + +struct bcm2835aux_data { + struct uart_8250_port uart; + struct clk *clk; + int line; +}; + +static int bcm2835aux_serial_probe(struct platform_device *pdev) +{ + struct bcm2835aux_data *data; + struct resource *res; + int ret; + + /* allocate the custom structure */ + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + /* initialize data */ + spin_lock_init(&data->uart.port.lock); + data->uart.capabilities = UART_CAP_FIFO; + data->uart.port.dev = &pdev->dev; + data->uart.port.regshift = 2; + data->uart.port.type = PORT_16550; + data->uart.port.iotype = UPIO_MEM; + data->uart.port.fifosize = 8; + data->uart.port.flags = UPF_SHARE_IRQ | + UPF_FIXED_PORT | + UPF_FIXED_TYPE | + UPF_SKIP_TEST; + + /* get the clock - this also enables the HW */ + data->clk = devm_clk_get(&pdev->dev, NULL); + ret = PTR_ERR_OR_ZERO(data->clk); + if (ret) { + dev_err(&pdev->dev, "could not get clk: %d\n", ret); + return ret; + } + + /* get the interrupt */ + ret = platform_get_irq(pdev, 0); + if (ret < 0) { + dev_err(&pdev->dev, "irq not found - %i", ret); + return ret; + } + data->uart.port.irq = ret; + + /* map the main registers */ + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) { + dev_err(&pdev->dev, "memory resource not found"); + return -EINVAL; + } + data->uart.port.membase = devm_ioremap_resource(&pdev->dev, res); + ret = PTR_ERR_OR_ZERO(data->uart.port.membase); + if (ret) + return ret; + + /* Check for a fixed line number */ + ret = of_alias_get_id(pdev->dev.of_node, "serial"); + if (ret >= 0) + data->uart.port.line = ret; + + /* enable the clock as a last step */ + ret = clk_prepare_enable(data->clk); + if (ret) { + dev_err(&pdev->dev, "unable to enable uart clock - %d\n", + ret); + return ret; + } + + /* the HW-clock divider for bcm2835aux is 8, + * but 8250 expects a divider of 16, + * so we have to multiply the actual clock by 2 + * to get identical baudrates. + */ + data->uart.port.uartclk = clk_get_rate(data->clk) * 2; + + /* register the port */ + ret = serial8250_register_8250_port(&data->uart); + if (ret < 0) { + dev_err(&pdev->dev, "unable to register 8250 port - %d\n", + ret); + goto dis_clk; + } + data->line = ret; + + platform_set_drvdata(pdev, data); + + return 0; + +dis_clk: + clk_disable_unprepare(data->clk); + return ret; +} + +static int bcm2835aux_serial_remove(struct platform_device *pdev) +{ + struct bcm2835aux_data *data = platform_get_drvdata(pdev); + + serial8250_unregister_port(data->uart.port.line); + clk_disable_unprepare(data->clk); + + return 0; +} + +static const struct of_device_id bcm2835aux_serial_match[] = { + { .compatible = "brcm,bcm2835-aux-uart" }, + { }, +}; +MODULE_DEVICE_TABLE(of, bcm2835aux_serial_match); + +static struct platform_driver bcm2835aux_serial_driver = { + .driver = { + .name = "bcm2835-aux-uart", + .of_match_table = bcm2835aux_serial_match, + }, + .probe = bcm2835aux_serial_probe, + .remove = bcm2835aux_serial_remove, +}; +module_platform_driver(bcm2835aux_serial_driver); + +MODULE_DESCRIPTION("BCM2835 auxiliar UART driver"); +MODULE_AUTHOR("Martin Sperl <kernel@martin.sperl.org>"); +MODULE_LICENSE("GPL v2"); |