serial: 8250_pci: Intel MID UART support to its own driver

Intel MID UART quirks require already quite a bit of code
in 8250_pci.c. On new Intel platforms where it is used, the
integrated DMA engine no longer has its own PCI device, but
is instead configured from the UART's MMIO. That means we
will have to add even more code for handling just MID UARTs.

Instead of adding that to 8250_pci.c, splitting the support
of Intel MID UART into its own driver. Handling of the
integrated DMA engine becomes much simpler this way. Own
driver will also remove the need for things like specific
set_termios hooks for every board using this UART, and
simplify the handling of it in general.

Signed-off-by: Heikki Krogerus <[email protected]>
Acked-by: Andy Shevchenko <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Heikki Krogerus

drivers/tty/serial/8250/8250_mid.c

@@ -0,0 +1,258 @@
+/*
+ * 8250_mid.c - Driver for UART on Intel Penwell and various other Intel SOCs
+ *
+ * Copyright (C) 2015 Intel Corporation
+ * Author: Heikki Krogerus <[email protected]>
+ *
+ * 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/rational.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+
+#include <linux/dma/hsu.h>
+
+#include "8250.h"
+
+#define PCI_DEVICE_ID_INTEL_PNW_UART1	0x081b
+#define PCI_DEVICE_ID_INTEL_PNW_UART2	0x081c
+#define PCI_DEVICE_ID_INTEL_PNW_UART3	0x081d
+#define PCI_DEVICE_ID_INTEL_TNG_UART	0x1191
+
+/* Intel MID Specific registers */
+#define INTEL_MID_UART_PS		0x30
+#define INTEL_MID_UART_MUL		0x34
+#define INTEL_MID_UART_DIV		0x38
+
+struct mid8250;
+
+struct mid8250_board {
+	unsigned long freq;
+	unsigned int base_baud;
+	int (*setup)(struct mid8250 *, struct uart_port *p);
+};
+
+struct mid8250 {
+	int line;
+	int dma_index;
+	struct pci_dev *dma_dev;
+	struct uart_8250_dma dma;
+	struct mid8250_board *board;
+};
+
+/*****************************************************************************/
+
+static int pnw_setup(struct mid8250 *mid, struct uart_port *p)
+{
+	struct pci_dev *pdev = to_pci_dev(p->dev);
+
+	switch (pdev->device) {
+	case PCI_DEVICE_ID_INTEL_PNW_UART1:
+		mid->dma_index = 0;
+		break;
+	case PCI_DEVICE_ID_INTEL_PNW_UART2:
+		mid->dma_index = 1;
+		break;
+	case PCI_DEVICE_ID_INTEL_PNW_UART3:
+		mid->dma_index = 2;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	mid->dma_dev = pci_get_slot(pdev->bus,
+				    PCI_DEVFN(PCI_SLOT(pdev->devfn), 3));
+	return 0;
+}
+
+static int tng_setup(struct mid8250 *mid, struct uart_port *p)
+{
+	struct pci_dev *pdev = to_pci_dev(p->dev);
+	int index = PCI_FUNC(pdev->devfn);
+
+	/* Currently no support for HSU port0 */
+	if (index-- == 0)
+		return -ENODEV;
+
+	mid->dma_index = index;
+	mid->dma_dev = pci_get_slot(pdev->bus, PCI_DEVFN(5, 0));
+	return 0;
+}
+
+/*****************************************************************************/
+
+static void mid8250_set_termios(struct uart_port *p,
+				struct ktermios *termios,
+				struct ktermios *old)
+{
+	unsigned int baud = tty_termios_baud_rate(termios);
+	struct mid8250 *mid = p->private_data;
+	unsigned short ps = 16;
+	unsigned long fuart = baud * ps;
+	unsigned long w = BIT(24) - 1;
+	unsigned long mul, div;
+
+	if (mid->board->freq < fuart) {
+		/* Find prescaler value that satisfies Fuart < Fref */
+		if (mid->board->freq > baud)
+			ps = mid->board->freq / baud;	/* baud rate too high */
+		else
+			ps = 1;				/* PLL case */
+		fuart = baud * ps;
+	} else {
+		/* Get Fuart closer to Fref */
+		fuart *= rounddown_pow_of_two(mid->board->freq / fuart);
+	}
+
+	rational_best_approximation(fuart, mid->board->freq, w, w, &mul, &div);
+	p->uartclk = fuart * 16 / ps;		/* core uses ps = 16 always */
+
+	writel(ps, p->membase + INTEL_MID_UART_PS);		/* set PS */
+	writel(mul, p->membase + INTEL_MID_UART_MUL);		/* set MUL */
+	writel(div, p->membase + INTEL_MID_UART_DIV);
+
+	serial8250_do_set_termios(p, termios, old);
+}
+
+static bool mid8250_dma_filter(struct dma_chan *chan, void *param)
+{
+	struct hsu_dma_slave *s = param;
+
+	if (s->dma_dev != chan->device->dev || s->chan_id != chan->chan_id)
+		return false;
+
+	chan->private = s;
+	return true;
+}
+
+static int mid8250_dma_setup(struct mid8250 *mid, struct uart_8250_port *port)
+{
+	struct uart_8250_dma *dma = &mid->dma;
+	struct device *dev = port->port.dev;
+	struct hsu_dma_slave *rx_param;
+	struct hsu_dma_slave *tx_param;
+
+	rx_param = devm_kzalloc(dev, sizeof(*rx_param), GFP_KERNEL);
+	if (!rx_param)
+		return -ENOMEM;
+
+	tx_param = devm_kzalloc(dev, sizeof(*tx_param), GFP_KERNEL);
+	if (!tx_param)
+		return -ENOMEM;
+
+	rx_param->chan_id = mid->dma_index * 2 + 1;
+	tx_param->chan_id = mid->dma_index * 2;
+
+	dma->rxconf.src_maxburst = 64;
+	dma->txconf.dst_maxburst = 64;
+
+	rx_param->dma_dev = &mid->dma_dev->dev;
+	tx_param->dma_dev = &mid->dma_dev->dev;
+
+	dma->fn = mid8250_dma_filter;
+	dma->rx_param = rx_param;
+	dma->tx_param = tx_param;
+
+	port->dma = dma;
+	return 0;
+}
+
+static int mid8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+	struct uart_8250_port uart;
+	struct mid8250 *mid;
+	int ret;
+
+	ret = pcim_enable_device(pdev);
+	if (ret)
+		return ret;
+
+	pci_set_master(pdev);
+
+	mid = devm_kzalloc(&pdev->dev, sizeof(*mid), GFP_KERNEL);
+	if (!mid)
+		return -ENOMEM;
+
+	mid->board = (struct mid8250_board *)id->driver_data;
+
+	memset(&uart, 0, sizeof(struct uart_8250_port));
+
+	uart.port.dev = &pdev->dev;
+	uart.port.irq = pdev->irq;
+	uart.port.private_data = mid;
+	uart.port.type = PORT_16750;
+	uart.port.iotype = UPIO_MEM;
+	uart.port.uartclk = mid->board->base_baud * 16;
+	uart.port.flags = UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE;
+	uart.port.set_termios = mid8250_set_termios;
+
+	uart.port.mapbase = pci_resource_start(pdev, 0);
+	uart.port.membase = pcim_iomap(pdev, 0, 0);
+	if (!uart.port.membase)
+		return -ENOMEM;
+
+	if (mid->board->setup) {
+		ret = mid->board->setup(mid, &uart.port);
+		if (ret)
+			return ret;
+	}
+
+	ret = mid8250_dma_setup(mid, &uart);
+	if (ret)
+		return ret;
+
+	ret = serial8250_register_8250_port(&uart);
+	if (ret < 0)
+		return ret;
+
+	mid->line = ret;
+
+	pci_set_drvdata(pdev, mid);
+	return 0;
+}
+
+static void mid8250_remove(struct pci_dev *pdev)
+{
+	struct mid8250 *mid = pci_get_drvdata(pdev);
+
+	serial8250_unregister_port(mid->line);
+}
+
+static const struct mid8250_board pnw_board = {
+	.freq = 50000000,
+	.base_baud = 115200,
+	.setup = pnw_setup,
+};
+
+static const struct mid8250_board tng_board = {
+	.freq = 38400000,
+	.base_baud = 1843200,
+	.setup = tng_setup,
+};
+
+#define MID_DEVICE(id, board) { PCI_VDEVICE(INTEL, id), (kernel_ulong_t)&board }
+
+static const struct pci_device_id pci_ids[] = {
+	MID_DEVICE(PCI_DEVICE_ID_INTEL_PNW_UART1, pnw_board),
+	MID_DEVICE(PCI_DEVICE_ID_INTEL_PNW_UART2, pnw_board),
+	MID_DEVICE(PCI_DEVICE_ID_INTEL_PNW_UART3, pnw_board),
+	MID_DEVICE(PCI_DEVICE_ID_INTEL_TNG_UART, tng_board),
+	{ },
+};
+MODULE_DEVICE_TABLE(pci, pci_ids);
+
+static struct pci_driver mid8250_pci_driver = {
+	.name           = "8250_mid",
+	.id_table       = pci_ids,
+	.probe          = mid8250_probe,
+	.remove         = mid8250_remove,
+};
+
+module_pci_driver(mid8250_pci_driver);
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Intel MID UART driver");