new file mode 100644
@@ -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 */
+ data->uart.port.irq = platform_get_irq(pdev, 0);
+ if (data->uart.port.irq < 0) {
+ dev_err(&pdev->dev, "irq not found - %i",
+ data->uart.port.irq);
+ return data->uart.port.irq;
+ }
+
+ /* 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");
@@ -272,6 +272,30 @@ config SERIAL_8250_ACORN
system, say Y to this option. The driver can handle 1, 2, or 3 port
cards. If unsure, say N.
+config SERIAL_8250_BCM2835AUX
+ tristate "BCM2835 auxiliar mini UART support"
+ depends on ARCH_BCM2835 || COMPILE_TEST
+ depends on SERIAL_8250 && SERIAL_8250_SHARE_IRQ
+ help
+ Support for the BCM2835 auxiliar mini UART.
+
+ Features and limitations of the UART are
+ Registers are similar to 16650 registers,
+ set bits in the control registers that are unsupported
+ are ignored and read back as 0
+ 7/8 bit operation with 1 start and 1 stop bit
+ 8 symbols deep fifo for rx and tx
+ SW controlled RTS and SW readable CTS
+ Clock rate derived from system clock
+ Uses 8 times oversampling (compared to 16 times for 16650)
+ Missing break detection (but break generation)
+ Missing framing error detection
+ Missing parity bit
+ Missing receive time-out interrupt
+ Missing DCD, DSR, DTR and RI signals
+
+ If unsure, say N.
+
config SERIAL_8250_FSL
bool
depends on SERIAL_8250_CONSOLE
@@ -12,6 +12,7 @@ obj-$(CONFIG_SERIAL_8250_PCI) += 8250_pci.o
obj-$(CONFIG_SERIAL_8250_HP300) += 8250_hp300.o
obj-$(CONFIG_SERIAL_8250_CS) += serial_cs.o
obj-$(CONFIG_SERIAL_8250_ACORN) += 8250_acorn.o
+obj-$(CONFIG_SERIAL_8250_BCM2835AUX) += 8250_bcm2835aux.o
obj-$(CONFIG_SERIAL_8250_CONSOLE) += 8250_early.o
obj-$(CONFIG_SERIAL_8250_FOURPORT) += 8250_fourport.o
obj-$(CONFIG_SERIAL_8250_ACCENT) += 8250_accent.o