/* pci.c - PCI probe and information routines */

/*
 * Copyright (c) 2013-2014 Wind River Systems, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1) Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2) Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3) Neither the name of Wind River Systems nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
DESCRIPTION
Module implements routines for PCI bus initialization and query.

USAGE
To use the driver, the platform must define:
- Numbers of BUSes:
    - PCI_BUS_NUMBERS;
- Register addresses:
    - PCI_CTRL_ADDR_REG;
    - PCI_CTRL_DATA_REG;
- pci_pin2irq() - the routine that converts the PCI interrupt pin
  number to IRQ number.

About scanning the PCI buses:
At every new usage of this API, the code should call pci_bus_scan_init().
It should own a struct pci_dev_info, filled in with the parameters it is
interested to look for: class and/or vendor_id/device_id.

Then it can loop on pci_bus_scan() providing a pointer on that structure.
Such function can be called as long as it returns 1. At every successful
return of pci_bus_scan() it means the provided structure pointer will have
been updated with the current scan result which the code might be interested
in. On pci_bus_scan() returning 0, the code should discard the result and
stop calling pci_bus_scan(). If it wants to retrieve the result, it will
have to restart the procedure all over again.

EXAMPLE
struct pci_dev_info info = {
	.class = PCI_CLASS_COMM_CTLR
};

pci_bus_scan_init();

while (pci_bus_scan(&info) {
	// do something with "info" which holds a valid result, i.e. some
	// device information matching the PCI class PCI_CLASS_COMM_CTLR
}

INTERNALS
The whole logic runs around a structure: struct lookup_data, which exists
on one instanciation called 'lookup'.
Such structure is used for 2 distinct roles:
- to match devices the caller is looking for
- to loop on PCI bus, devices, function and BARs

The search criterias are the class and/or the vendor_id/device_id of a PCI
device. The caller first initializes the lookup structure by calling
pci_bus_scan_init(), which will reset the search criterias as well as the
loop paramaters to 0. At the very first subsequent call of pci_bus_scan()
the lookup structure will store the search criterias. Then the loop starts.
For each bus it will run through each device on which it will loop on each
function and BARs, as long as the criterias does not match or until it hit
the limit of bus/dev/functions to scan.

On a successful match, it will stop the loop, fill in the caller's
pci_dev_info structure with the found device information, and return 1.
Hopefully, the lookup structure still remembers where it stopped and the
original search criterias. Thus, when the caller asks to scan again for
a possible result next, the loop will restart where it stopped.
That will work as long as there are relevant results found.

 */

#include <nanokernel.h>
#include <arch/cpu.h>
#include <misc/printk.h>
#include <toolchain.h>
#include <sections.h>

#include <board.h>

#include <pci/pci_mgr.h>
#include <pci/pci.h>

#ifdef CONFIG_PCI_ENUMERATION

/* NOTE. These parameters may need to be configurable */
#define LSPCI_MAX_BUS PCI_BUS_NUMBERS /* maximum number of buses to scan */
#define LSPCI_MAX_DEV 32  /* maximum number of devices to scan */
#define LSPCI_MAX_FUNC PCI_MAX_FUNCTIONS  /* maximum functions to scan */
#define LSPCI_MAX_REG 64  /* maximum device registers to read */

/* Base Address Register configuration fields */

#define BAR_SPACE(x) ((x) & 0x00000001)

#define BAR_TYPE(x) ((x) & 0x00000006)
#define BAR_TYPE_32BIT 0
#define BAR_TYPE_64BIT 4

#define BAR_PREFETCH(x) (((x) >> 3) & 0x00000001)
#define BAR_ADDR(x) (((x) >> 4) & 0x0fffffff)

#define BAR_IO_MASK(x) ((x) & ~0x3)
#define BAR_MEM_MASK(x) ((x) & ~0xf)


struct lookup_data {
	struct pci_dev_info info;
	uint32_t bus:9;
	uint32_t dev:6;
	uint32_t func:4;
	uint32_t bar:4;
	uint32_t unused:9;
};

static struct lookup_data __noinit lookup;

/**
 *
 * @brief Return the configuration for the specified BAR
 *
 * @return 0 if BAR is implemented, -1 if not.
 */

static inline int pci_bar_config_get(union pci_addr_reg pci_ctrl_addr,
							uint32_t *config)
{
	uint32_t old_value;

	/* save the current setting */
	pci_read(DEFAULT_PCI_CONTROLLER,
			pci_ctrl_addr,
			sizeof(old_value),
			&old_value);

	/* write to the BAR to see how large it is */
	pci_write(DEFAULT_PCI_CONTROLLER,
			pci_ctrl_addr,
			sizeof(uint32_t),
			0xffffffff);

	pci_read(DEFAULT_PCI_CONTROLLER,
			pci_ctrl_addr,
			sizeof(*config),
			config);

	/* put back the old configuration */
	pci_write(DEFAULT_PCI_CONTROLLER,
			pci_ctrl_addr,
			sizeof(old_value),
			old_value);

	/* check if this BAR is implemented */
	if (*config != 0xffffffff && *config != 0) {
		return 0;
	}

	/* BAR not supported */

	return -1;
}

/**
 *
 * @brief Retrieve the I/O address and IRQ of the specified BAR
 *
 * @return -1 on error, 0 if 32 bit BAR retrieved or 1 if 64 bit BAR retrieved
 *
 * NOTE: Routine does not set up parameters for 64 bit BARS, they are ignored.
 *
 * \NOMANUAL
 */

static inline int pci_bar_params_get(union pci_addr_reg pci_ctrl_addr,
					struct pci_dev_info *dev_info)
{
	uint32_t bar_value;
	uint32_t bar_config;
	uint32_t addr;
	uint32_t mask;

	pci_ctrl_addr.field.reg = 4 + lookup.bar;

	pci_read(DEFAULT_PCI_CONTROLLER,
			pci_ctrl_addr,
			sizeof(bar_value),
			&bar_value);
	if (pci_bar_config_get(pci_ctrl_addr, &bar_config) != 0) {
		return -1;
	}

	if (BAR_SPACE(bar_config) == BAR_SPACE_MEM) {
		dev_info->mem_type = BAR_SPACE_MEM;
		mask = ~0xf;
		if (lookup.bar < 5 && BAR_TYPE(bar_config) == BAR_TYPE_64BIT) {
			return 1; /* 64-bit MEM */
		}
	} else {
		dev_info->mem_type = BAR_SPACE_IO;
		mask = ~0x3;
	}

	dev_info->addr = bar_value & mask;

	addr = bar_config & mask;
	if (addr != 0) {
		/* calculate the size of the BAR memory required */
		dev_info->size = 1 << (find_lsb_set(addr) - 1);
	}

	return 0;
}

/**
 *
 * @brief Scan the specified PCI device for all sub functions
 *
 * @return 1 if a device has been found, 0 otherwise.
 *
 * \NOMANUAL
 */

static inline int pci_dev_scan(union pci_addr_reg pci_ctrl_addr,
					struct pci_dev_info *dev_info)
{
	static union pci_dev pci_dev_header;
	uint32_t pci_data;
	int max_bars;

	/* verify first if there is a valid device at this point */
	pci_ctrl_addr.field.func = 0;

	pci_read(DEFAULT_PCI_CONTROLLER,
			pci_ctrl_addr,
			sizeof(pci_data),
			&pci_data);

	if (pci_data == 0xffffffff) {
		return 0;
	}

	/* scan all the possible functions for this device */
	for (; lookup.func < LSPCI_MAX_FUNC; lookup.bar = 0, lookup.func++) {
		if (lookup.info.function != PCI_FUNCTION_ANY &&
		    lookup.func != lookup.info.function) {
			return 0;
		}

		pci_ctrl_addr.field.func = lookup.func;

		if (lookup.func != 0) {
			pci_read(DEFAULT_PCI_CONTROLLER,
					pci_ctrl_addr,
					sizeof(pci_data),
					&pci_data);

			if (pci_data == 0xffffffff) {
				continue;
			}
		}

		/* get the PCI header from the device */
		pci_header_get(DEFAULT_PCI_CONTROLLER,
					pci_ctrl_addr,
					&pci_dev_header);

		/*
		 * Skip a device if its class is specified by the
		 * caller and does not match
		 */
		if (lookup.info.class &&
		    pci_dev_header.field.class != lookup.info.class) {
			continue;
		}

		if (lookup.info.vendor_id && lookup.info.device_id &&
		    (lookup.info.vendor_id != pci_dev_header.field.vendor_id ||
		    lookup.info.device_id != pci_dev_header.field.device_id)) {
			continue;
		}

		/* Get memory and interrupt information */
		if ((pci_dev_header.field.hdr_type & 0x7f) == 1) {
			max_bars = 2;
		} else {
			max_bars = PCI_MAX_BARS;
		}

		for (; lookup.bar < max_bars; lookup.bar++) {
			/* Ignore BARs with errors and 64 bit BARs */
			if (pci_bar_params_get(pci_ctrl_addr, dev_info) != 0) {
				continue;
			} else if (lookup.info.bar != PCI_BAR_ANY &&
				   lookup.bar != lookup.info.bar) {
				continue;
			} else {
				dev_info->vendor_id =
					pci_dev_header.field.vendor_id;
				dev_info->device_id =
					pci_dev_header.field.device_id;
				dev_info->class =
					pci_dev_header.field.class;
				dev_info->irq = pci_pin2irq(
					pci_dev_header.field.interrupt_pin);
				dev_info->function = lookup.func;
				dev_info->bar = lookup.bar;

				lookup.bar++;
				if (lookup.bar >= max_bars)
					lookup.bar = 0;

				return 1;
			}
		}
	}

	return 0;
}

void pci_bus_scan_init(void)
{
	lookup.info.class = 0;
	lookup.info.vendor_id = 0;
	lookup.info.device_id = 0;
	lookup.info.function = PCI_FUNCTION_ANY;
	lookup.info.bar = PCI_BAR_ANY;
	lookup.bus = 0;
	lookup.dev = 0;
	lookup.func = 0;
	lookup.bar = 0;
}


/**
 *
 * @brief Scans PCI bus for devices
 *
 * The routine scans the PCI bus for the devices on criterias provided in the
 * given dev_info at first call. Which criterias can be class and/or
 * vendor_id/device_id.
 *
 * @return 1 on success, 0 otherwise. On success, dev_info is filled in with
 * currently found device information
 *
 * \NOMANUAL
 */

int pci_bus_scan(struct pci_dev_info *dev_info)
{
	union pci_addr_reg pci_ctrl_addr;

	if (!lookup.info.class &&
	    !lookup.info.vendor_id &&
	    !lookup.info.device_id &&
	    lookup.info.bar == PCI_BAR_ANY &&
	    lookup.info.function == PCI_FUNCTION_ANY) {
		lookup.info.class = dev_info->class;
		lookup.info.vendor_id = dev_info->vendor_id;
		lookup.info.device_id = dev_info->device_id;
		lookup.info.function = dev_info->function;
		lookup.info.bar = dev_info->bar;
	}

	/* initialise the PCI controller address register value */
	pci_ctrl_addr.value = 0;

	if (lookup.info.function != PCI_FUNCTION_ANY) {
		lookup.func = lookup.info.function;
	}

	/* run through the buses and devices */
	for (; lookup.bus < LSPCI_MAX_BUS; lookup.bus++) {
		for (; (lookup.dev < LSPCI_MAX_DEV); lookup.dev++) {
			pci_ctrl_addr.field.bus = lookup.bus;
			pci_ctrl_addr.field.device = lookup.dev;

			if (pci_dev_scan(pci_ctrl_addr, dev_info)) {
				dev_info->bus = lookup.bus;
				dev_info->dev = lookup.dev;

				return 1;
			}

			if (lookup.info.function != PCI_FUNCTION_ANY) {
				lookup.func = lookup.info.function;
			} else {
				lookup.func = 0;
			}
		}
	}

	return 0;
}
#endif /* CONFIG_PCI_ENUMERATION */

void pci_enable_regs(struct pci_dev_info *dev_info)
{
	union pci_addr_reg pci_ctrl_addr;
	uint32_t pci_data;

	pci_ctrl_addr.value = 0;
	pci_ctrl_addr.field.func = dev_info->function;
	pci_ctrl_addr.field.bus = dev_info->bus;
	pci_ctrl_addr.field.device = dev_info->dev;
	pci_ctrl_addr.field.reg = 1;

#ifdef CONFIG_PCI_DEBUG
	printk("pci_enable_regs 0x%x\n", pci_ctrl_addr);
#endif

	pci_read(DEFAULT_PCI_CONTROLLER,
			pci_ctrl_addr,
			sizeof(uint16_t),
			&pci_data);

	pci_data = pci_data | PCI_CMD_MEM_ENABLE;

	pci_write(DEFAULT_PCI_CONTROLLER,
			pci_ctrl_addr,
			sizeof(uint16_t),
			pci_data);
}

#ifdef CONFIG_PCI_DEBUG
/**
 *
 * @brief Show PCI device
 *
 * Shows the PCI device found provided as parameter.
 *
 * @return N/A
 */

void pci_show(struct pci_dev_info *dev_info)
{
	printk("PCI device:\n");
	printk("%u:%u %X:%X class: 0x%X, %u, %u, %s,"
		"addrs: 0x%X-0x%X, IRQ %d\n",
		dev_info->bus,
		dev_info->dev,
		dev_info->vendor_id,
		dev_info->device_id,
		dev_info->class,
		dev_info->function,
		dev_info->bar,
		(dev_info->mem_type == BAR_SPACE_MEM) ? "MEM" : "I/O",
		(uint32_t)dev_info->addr,
		(uint32_t)(dev_info->addr + dev_info->size - 1),
		dev_info->irq);
}
#endif /* CONFIG_PCI_DEBUG */