serial: serial_octeon_pcie_console.c: Add PCI remote console support

This patch adds the PCI remote console feature for MIPS Octeon, which
will be used by the upcoming Octeon III NIC23 board support. It enables
the use of the "oct-remote-console" tool on host PC's to communicate
with the PCIe target.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Aaron Williams <awilliams@marvell.com>
Cc: Chandrakala Chavva <cchavva@marvell.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

drivers/serial/Kconfig

@@ -788,6 +788,19 @@ config MSM_SERIAL
 	  for example APQ8016 and MSM8916.
 	  Single baudrate is supported in current implementation (115200).
 
+config OCTEON_SERIAL_PCIE_CONSOLE
+	bool "MIPS Octeon PCIe remote console"
+	depends on ARCH_OCTEON
+	depends on (DM_SERIAL && DM_STDIO)
+	select SYS_STDIO_DEREGISTER
+	select SYS_CONSOLE_IS_IN_ENV
+	select CONSOLE_MUX
+	help
+	  This driver supports remote console over the PCIe bus when the
+	  Octeon is running in PCIe target mode. The host program
+	  'oct-remote-console' can be used to connect to this console.
+	  The console number will likely be 0 or 1.
+
 config OMAP_SERIAL
 	bool "Support for OMAP specific UART"
 	depends on DM_SERIAL

drivers/serial/Makefile

@@ -66,6 +66,7 @@ obj-$(CONFIG_MSM_SERIAL) += serial_msm.o
 obj-$(CONFIG_MVEBU_A3700_UART) += serial_mvebu_a3700.o
 obj-$(CONFIG_MPC8XX_CONS) += serial_mpc8xx.o
 obj-$(CONFIG_NULLDEV_SERIAL) += serial_nulldev.o
+obj-$(CONFIG_OCTEON_SERIAL_PCIE_CONSOLE) += serial_octeon_pcie_console.o
 obj-$(CONFIG_OWL_SERIAL) += serial_owl.o
 obj-$(CONFIG_OMAP_SERIAL) += serial_omap.o
 obj-$(CONFIG_MTK_SERIAL) += serial_mtk.o

drivers/serial/serial_octeon_pcie_console.c

@@ -0,0 +1,365 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Marvell International Ltd.
+ * Copyright (C) 2021 Stefan Roese <sr@denx.de>
+ */
+
+#include <dm.h>
+#include <dm/uclass.h>
+#include <errno.h>
+#include <input.h>
+#include <iomux.h>
+#include <log.h>
+#include <serial.h>
+#include <stdio_dev.h>
+#include <string.h>
+#include <watchdog.h>
+#include <linux/delay.h>
+#include <asm/io.h>
+#include <mach/cvmx-regs.h>
+#include <mach/cvmx-bootmem.h>
+
+#define DRIVER_NAME				"pci-console"
+#define OCTEONTX_PCIE_CONSOLE_NAME_LEN		16
+
+/* Current versions */
+#define OCTEON_PCIE_CONSOLE_MAJOR_VERSION	1
+#define OCTEON_PCIE_CONSOLE_MINOR_VERSION	0
+
+#define OCTEON_PCIE_CONSOLE_BLOCK_NAME		"__pci_console"
+
+/*
+ * Structure that defines a single console.
+ * Note: when read_index == write_index, the buffer is empty.
+ * The actual usable size of each console is console_buf_size -1;
+ */
+struct octeon_pcie_console {
+	u64 input_base_addr;
+	u32 input_read_index;
+	u32 input_write_index;
+	u64 output_base_addr;
+	u32 output_read_index;
+	u32 output_write_index;
+	u32 lock;
+	u32 buf_size;
+};
+
+/*
+ * This is the main container structure that contains all the information
+ * about all PCI consoles. The address of this structure is passed to various
+ * routines that operation on PCI consoles.
+ */
+struct octeon_pcie_console_desc {
+	u32 major_version;
+	u32 minor_version;
+	u32 lock;
+	u32 flags;
+	u32 num_consoles;
+	u32 pad;
+	/* must be 64 bit aligned here... */
+	/* Array of addresses of octeon_pcie_console_t structures */
+	u64 console_addr_array[0];
+	/* Implicit storage for console_addr_array */
+};
+
+struct octeon_pcie_console_priv {
+	struct octeon_pcie_console *console;
+	int console_num;
+	bool console_active;
+};
+
+/* Flag definitions for read/write functions */
+enum {
+	/*
+	 * If set, read/write functions won't block waiting for space or data.
+	 * For reads, 0 bytes may be read, and for writes not all of the
+	 * supplied data may be written.
+	 */
+	OCT_PCI_CON_FLAG_NONBLOCK = 1 << 0,
+};
+
+static int buffer_free_bytes(u32 buffer_size, u32 wr_idx, u32 rd_idx)
+{
+	if (rd_idx >= buffer_size || wr_idx >= buffer_size)
+		return -1;
+
+	return ((buffer_size - 1) - (wr_idx - rd_idx)) % buffer_size;
+}
+
+static int buffer_avail_bytes(u32 buffer_size, u32 wr_idx, u32 rd_idx)
+{
+	if (rd_idx >= buffer_size || wr_idx >= buffer_size)
+		return -1;
+
+	return buffer_size - 1 - buffer_free_bytes(buffer_size, wr_idx, rd_idx);
+}
+
+static int buffer_read_avail(struct udevice *dev, unsigned int console_num)
+{
+	struct octeon_pcie_console_priv *priv = dev_get_priv(dev);
+	struct octeon_pcie_console *cons_ptr = priv->console;
+	int avail;
+
+	avail = buffer_avail_bytes(cons_ptr->buf_size,
+				   cons_ptr->input_write_index,
+				   cons_ptr->input_read_index);
+	if (avail >= 0)
+		return avail;
+
+	return 0;
+}
+
+static int octeon_pcie_console_read(struct udevice *dev,
+				    unsigned int console_num, char *buffer,
+				    int buffer_size, u32 flags)
+{
+	struct octeon_pcie_console_priv *priv = dev_get_priv(dev);
+	struct octeon_pcie_console *cons_ptr = priv->console;
+	int avail;
+	char *buf_ptr;
+	int bytes_read;
+	int read_size;
+
+	buf_ptr = (char *)cvmx_phys_to_ptr(cons_ptr->input_base_addr);
+
+	avail =	buffer_avail_bytes(cons_ptr->buf_size,
+				   cons_ptr->input_write_index,
+				   cons_ptr->input_read_index);
+	if (avail < 0)
+		return avail;
+
+	if (!(flags & OCT_PCI_CON_FLAG_NONBLOCK)) {
+		/* Wait for some data to be available */
+		while (0 == (avail = buffer_avail_bytes(cons_ptr->buf_size,
+							cons_ptr->input_write_index,
+							cons_ptr->input_read_index))) {
+			mdelay(10);
+			WATCHDOG_RESET();
+		}
+	}
+
+	bytes_read = 0;
+
+	/* Don't overflow the buffer passed to us */
+	read_size = min_t(int, avail, buffer_size);
+
+	/* Limit ourselves to what we can input in a contiguous block */
+	if (cons_ptr->input_read_index + read_size >= cons_ptr->buf_size)
+		read_size = cons_ptr->buf_size - cons_ptr->input_read_index;
+
+	memcpy(buffer, buf_ptr + cons_ptr->input_read_index, read_size);
+	cons_ptr->input_read_index =
+		(cons_ptr->input_read_index + read_size) % cons_ptr->buf_size;
+	bytes_read += read_size;
+
+	/* Mark the PCIe console to be active from now on */
+	if (bytes_read)
+		priv->console_active = true;
+
+	return bytes_read;
+}
+
+static int octeon_pcie_console_write(struct udevice *dev,
+				     unsigned int console_num,
+				     const char *buffer,
+				     int bytes_to_write, u32 flags)
+{
+	struct octeon_pcie_console_priv *priv = dev_get_priv(dev);
+	struct octeon_pcie_console *cons_ptr = priv->console;
+	int avail;
+	char *buf_ptr;
+	int bytes_written;
+
+	buf_ptr = (char *)cvmx_phys_to_ptr(cons_ptr->output_base_addr);
+	bytes_written = 0;
+	while (bytes_to_write > 0) {
+		avail = buffer_free_bytes(cons_ptr->buf_size,
+					  cons_ptr->output_write_index,
+					  cons_ptr->output_read_index);
+
+		if (avail > 0) {
+			int write_size = min_t(int, avail, bytes_to_write);
+
+			/*
+			 * Limit ourselves to what we can output in a contiguous
+			 * block
+			 */
+			if (cons_ptr->output_write_index + write_size >=
+			    cons_ptr->buf_size) {
+				write_size = cons_ptr->buf_size -
+					     cons_ptr->output_write_index;
+			}
+
+			memcpy(buf_ptr + cons_ptr->output_write_index,
+			       buffer + bytes_written, write_size);
+			/*
+			 * Make sure data is visible before changing write
+			 * index
+			 */
+			CVMX_SYNCW;
+			cons_ptr->output_write_index =
+				(cons_ptr->output_write_index + write_size) %
+				cons_ptr->buf_size;
+			bytes_to_write -= write_size;
+			bytes_written += write_size;
+		} else if (avail == 0) {
+			/*
+			 * Check to see if we should wait for room, or return
+			 * after a partial write
+			 */
+			if (flags & OCT_PCI_CON_FLAG_NONBLOCK)
+				goto done;
+
+			WATCHDOG_RESET();
+			mdelay(10);	/* Delay if we are spinning */
+		} else {
+			bytes_written = -1;
+			goto done;
+		}
+	}
+
+done:
+	return bytes_written;
+}
+
+static struct octeon_pcie_console_desc *octeon_pcie_console_init(int num_consoles,
+								 int buffer_size)
+{
+	struct octeon_pcie_console_desc *cons_desc_ptr;
+	struct octeon_pcie_console *cons_ptr;
+	s64 addr;
+	u64 avail_addr;
+	int alloc_size;
+	int i;
+
+	/* Compute size required for pci console structure */
+	alloc_size = num_consoles *
+		(buffer_size * 2 + sizeof(struct octeon_pcie_console) +
+		 sizeof(u64)) + sizeof(struct octeon_pcie_console_desc);
+
+	/*
+	 * Allocate memory for the consoles.  This must be in the range
+	 * addresssible by the bootloader.
+	 * Try to do so in a manner which minimizes fragmentation.  We try to
+	 * put it at the top of DDR0 or bottom of DDR2 first, and only do
+	 * generic allocation if those fail
+	 */
+	addr = cvmx_bootmem_phy_named_block_alloc(alloc_size,
+						  OCTEON_DDR0_SIZE - alloc_size - 128,
+						  OCTEON_DDR0_SIZE, 128,
+						  OCTEON_PCIE_CONSOLE_BLOCK_NAME,
+						  CVMX_BOOTMEM_FLAG_END_ALLOC);
+	if (addr < 0) {
+		addr = cvmx_bootmem_phy_named_block_alloc(alloc_size, 0,
+							  0x1fffffff, 128,
+							  OCTEON_PCIE_CONSOLE_BLOCK_NAME,
+							  CVMX_BOOTMEM_FLAG_END_ALLOC);
+	}
+	if (addr < 0)
+		return 0;
+
+	cons_desc_ptr = cvmx_phys_to_ptr(addr);
+
+	/* Clear entire alloc'ed memory */
+	memset(cons_desc_ptr, 0, alloc_size);
+
+	/* Initialize as locked until we are done */
+	cons_desc_ptr->lock = 1;
+	CVMX_SYNCW;
+	cons_desc_ptr->num_consoles = num_consoles;
+	cons_desc_ptr->flags = 0;
+	cons_desc_ptr->major_version = OCTEON_PCIE_CONSOLE_MAJOR_VERSION;
+	cons_desc_ptr->minor_version = OCTEON_PCIE_CONSOLE_MINOR_VERSION;
+
+	avail_addr = addr + sizeof(struct octeon_pcie_console_desc) +
+		num_consoles * sizeof(u64);
+
+	for (i = 0; i < num_consoles; i++) {
+		cons_desc_ptr->console_addr_array[i] = avail_addr;
+		cons_ptr = (void *)cons_desc_ptr->console_addr_array[i];
+		avail_addr += sizeof(struct octeon_pcie_console);
+		cons_ptr->input_base_addr = avail_addr;
+		avail_addr += buffer_size;
+		cons_ptr->output_base_addr = avail_addr;
+		avail_addr += buffer_size;
+		cons_ptr->buf_size = buffer_size;
+	}
+	CVMX_SYNCW;
+	cons_desc_ptr->lock = 0;
+
+	return cvmx_phys_to_ptr(addr);
+}
+
+static int octeon_pcie_console_getc(struct udevice *dev)
+{
+	char c;
+
+	octeon_pcie_console_read(dev, 0, &c, 1, 0);
+	return c;
+}
+
+static int octeon_pcie_console_putc(struct udevice *dev, const char c)
+{
+	struct octeon_pcie_console_priv *priv = dev_get_priv(dev);
+
+	if (priv->console_active)
+		octeon_pcie_console_write(dev, 0, (char *)&c, 1, 0);
+
+	return 0;
+}
+
+static int octeon_pcie_console_pending(struct udevice *dev, bool input)
+{
+	if (input) {
+		udelay(100);
+		return buffer_read_avail(dev, 0) > 0;
+	}
+
+	return 0;
+}
+
+static const struct dm_serial_ops octeon_pcie_console_ops = {
+	.getc = octeon_pcie_console_getc,
+	.putc = octeon_pcie_console_putc,
+	.pending = octeon_pcie_console_pending,
+};
+
+static int octeon_pcie_console_probe(struct udevice *dev)
+{
+	struct octeon_pcie_console_priv *priv = dev_get_priv(dev);
+	struct octeon_pcie_console_desc *cons_desc;
+	int console_count;
+	int console_size;
+	int console_num;
+
+	/*
+	 * Currently only 1 console is supported. Perhaps we need to add
+	 * a console nexus if more than one needs to be supported.
+	 */
+	console_count = 1;
+	console_size = 1024;
+	console_num = 0;
+
+	cons_desc = octeon_pcie_console_init(console_count, console_size);
+	priv->console =
+		cvmx_phys_to_ptr(cons_desc->console_addr_array[console_num]);
+
+	debug("PCI console init succeeded, %d consoles, %d bytes each\n",
+	      console_count, console_size);
+
+	return 0;
+}
+
+static const struct udevice_id octeon_pcie_console_serial_id[] = {
+	{ .compatible = "marvell,pci-console", },
+	{ },
+};
+
+U_BOOT_DRIVER(octeon_pcie_console) = {
+	.name = DRIVER_NAME,
+	.id = UCLASS_SERIAL,
+	.ops = &octeon_pcie_console_ops,
+	.of_match = of_match_ptr(octeon_pcie_console_serial_id),
+	.probe = octeon_pcie_console_probe,
+	.priv_auto = sizeof(struct octeon_pcie_console_priv),
+};