--- /dev/null
+/*
+ * 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");
projects / firefly-linux-kernel-4.4.55.git / commitdiff