/*
   * Simple, generic PCI host controller driver targetting firmware-initialised
   * systems and virtual machines (e.g. the PCI emulation provided by kvmtool).
   *
   * 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.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   * Copyright (C) 2014 ARM Limited
   *
   * Author: Will Deacon <will.deacon@arm.com>
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/of_address.h>
  #include <linux/of_pci.h>
  #include <linux/platform_device.h>
  
  struct gen_pci_cfg_bus_ops {
  	u32 bus_shift;
  	void __iomem *(*map_bus)(struct pci_bus *, unsigned int, int);
  };
  
  struct gen_pci_cfg_windows {
  	struct resource				res;
  	struct resource				bus_range;
  	void __iomem				**win;
  
  	const struct gen_pci_cfg_bus_ops	*ops;
  };
  
  struct gen_pci {
  	struct pci_host_bridge			host;
  	struct gen_pci_cfg_windows		cfg;
  	struct list_head			resources;
  };
  
  static void __iomem *gen_pci_map_cfg_bus_cam(struct pci_bus *bus,
  					     unsigned int devfn,
  					     int where)
  {
  	struct pci_sys_data *sys = bus->sysdata;
  	struct gen_pci *pci = sys->private_data;
  	resource_size_t idx = bus->number - pci->cfg.bus_range.start;
  
  	return pci->cfg.win[idx] + ((devfn << 8) | where);
  }
  
  static struct gen_pci_cfg_bus_ops gen_pci_cfg_cam_bus_ops = {
  	.bus_shift	= 16,
  	.map_bus	= gen_pci_map_cfg_bus_cam,
  };
  
  static void __iomem *gen_pci_map_cfg_bus_ecam(struct pci_bus *bus,
  					      unsigned int devfn,
  					      int where)
  {
  	struct pci_sys_data *sys = bus->sysdata;
  	struct gen_pci *pci = sys->private_data;
  	resource_size_t idx = bus->number - pci->cfg.bus_range.start;
  
  	return pci->cfg.win[idx] + ((devfn << 12) | where);
  }
  
  static struct gen_pci_cfg_bus_ops gen_pci_cfg_ecam_bus_ops = {
  	.bus_shift	= 20,
  	.map_bus	= gen_pci_map_cfg_bus_ecam,
  };
  
  static int gen_pci_config_read(struct pci_bus *bus, unsigned int devfn,
  				int where, int size, u32 *val)
  {
  	void __iomem *addr;
  	struct pci_sys_data *sys = bus->sysdata;
  	struct gen_pci *pci = sys->private_data;
  
  	addr = pci->cfg.ops->map_bus(bus, devfn, where);
  
  	switch (size) {
  	case 1:
  		*val = readb(addr);
  		break;
  	case 2:
  		*val = readw(addr);
  		break;
  	default:
  		*val = readl(addr);
  	}
  
  	return PCIBIOS_SUCCESSFUL;
  }
  
  static int gen_pci_config_write(struct pci_bus *bus, unsigned int devfn,
  				 int where, int size, u32 val)
  {
  	void __iomem *addr;
  	struct pci_sys_data *sys = bus->sysdata;
  	struct gen_pci *pci = sys->private_data;
  
  	addr = pci->cfg.ops->map_bus(bus, devfn, where);
  
  	switch (size) {
  	case 1:
  		writeb(val, addr);
  		break;
  	case 2:
  		writew(val, addr);
  		break;
  	default:
  		writel(val, addr);
  	}
  
  	return PCIBIOS_SUCCESSFUL;
  }
  
  static struct pci_ops gen_pci_ops = {
  	.read	= gen_pci_config_read,
  	.write	= gen_pci_config_write,
  };
  
  static const struct of_device_id gen_pci_of_match[] = {
  	{ .compatible = "pci-host-cam-generic",
  	  .data = &gen_pci_cfg_cam_bus_ops },
  
  	{ .compatible = "pci-host-ecam-generic",
  	  .data = &gen_pci_cfg_ecam_bus_ops },
  
  	{ },
  };
  MODULE_DEVICE_TABLE(of, gen_pci_of_match);
  
  static int gen_pci_calc_io_offset(struct device *dev,
  				  struct of_pci_range *range,
  				  struct resource *res,
  				  resource_size_t *offset)
  {
  	static atomic_t wins = ATOMIC_INIT(0);
  	int err, idx, max_win;
  	unsigned int window;
  
  	if (!PAGE_ALIGNED(range->cpu_addr))
  		return -EINVAL;
  
  	max_win = (IO_SPACE_LIMIT + 1) / SZ_64K;
  	idx = atomic_inc_return(&wins);
  	if (idx > max_win)
  		return -ENOSPC;
  
  	window = (idx - 1) * SZ_64K;
  	err = pci_ioremap_io(window, range->cpu_addr);
  	if (err)
  		return err;
  
  	of_pci_range_to_resource(range, dev->of_node, res);
  	res->start = window;
  	res->end = res->start + range->size - 1;
  	*offset = window - range->pci_addr;
  	return 0;
  }
  
  static int gen_pci_calc_mem_offset(struct device *dev,
  				   struct of_pci_range *range,
  				   struct resource *res,
  				   resource_size_t *offset)
  {
  	of_pci_range_to_resource(range, dev->of_node, res);
  	*offset = range->cpu_addr - range->pci_addr;
  	return 0;
  }
  
  static void gen_pci_release_of_pci_ranges(struct gen_pci *pci)
  {
  	struct pci_host_bridge_window *win;
  
  	list_for_each_entry(win, &pci->resources, list)
  		release_resource(win->res);
  
  	pci_free_resource_list(&pci->resources);
  }
  
  static int gen_pci_parse_request_of_pci_ranges(struct gen_pci *pci)
  {
  	struct of_pci_range range;
  	struct of_pci_range_parser parser;
  	int err, res_valid = 0;
  	struct device *dev = pci->host.dev.parent;
  	struct device_node *np = dev->of_node;
  
  	if (of_pci_range_parser_init(&parser, np)) {
  		dev_err(dev, "missing \"ranges\" property
  ");
  		return -EINVAL;
  	}
  
  	for_each_of_pci_range(&parser, &range) {
  		struct resource *parent, *res;
  		resource_size_t offset;
  		u32 restype = range.flags & IORESOURCE_TYPE_BITS;
  
  		res = devm_kmalloc(dev, sizeof(*res), GFP_KERNEL);
  		if (!res) {
  			err = -ENOMEM;
  			goto out_release_res;
  		}
  
  		switch (restype) {
  		case IORESOURCE_IO:
  			parent = &ioport_resource;
  			err = gen_pci_calc_io_offset(dev, &range, res, &offset);
  			break;
  		case IORESOURCE_MEM:
  			parent = &iomem_resource;
  			err = gen_pci_calc_mem_offset(dev, &range, res, &offset);
  			res_valid |= !(res->flags & IORESOURCE_PREFETCH || err);
  			break;
  		default:
  			err = -EINVAL;
  			continue;
  		}
  
  		if (err) {
  			dev_warn(dev,
  				 "error %d: failed to add resource [type 0x%x, %lld bytes]
  ",
  				 err, restype, range.size);
  			continue;
  		}
  
  		err = request_resource(parent, res);
  		if (err)
  			goto out_release_res;
  
  		pci_add_resource_offset(&pci->resources, res, offset);
  	}
  
  	if (!res_valid) {
  		dev_err(dev, "non-prefetchable memory resource required
  ");
  		err = -EINVAL;
  		goto out_release_res;
  	}
  
  	return 0;
  
  out_release_res:
  	gen_pci_release_of_pci_ranges(pci);
  	return err;
  }
  
  static int gen_pci_parse_map_cfg_windows(struct gen_pci *pci)
  {
  	int err;
  	u8 bus_max;
  	resource_size_t busn;
  	struct resource *bus_range;
  	struct device *dev = pci->host.dev.parent;
  	struct device_node *np = dev->of_node;
  
  	if (of_pci_parse_bus_range(np, &pci->cfg.bus_range))
  		pci->cfg.bus_range = (struct resource) {
  			.name	= np->name,
  			.start	= 0,
  			.end	= 0xff,
  			.flags	= IORESOURCE_BUS,
  		};
  
  	err = of_address_to_resource(np, 0, &pci->cfg.res);
  	if (err) {
  		dev_err(dev, "missing \"reg\" property
  ");
  		return err;
  	}
  
  	pci->cfg.win = devm_kcalloc(dev, resource_size(&pci->cfg.bus_range),
  				    sizeof(*pci->cfg.win), GFP_KERNEL);
  	if (!pci->cfg.win)
  		return -ENOMEM;
  
  	/* Limit the bus-range to fit within reg */
  	bus_max = pci->cfg.bus_range.start +
  		  (resource_size(&pci->cfg.res) >> pci->cfg.ops->bus_shift) - 1;
  	pci->cfg.bus_range.end = min_t(resource_size_t, pci->cfg.bus_range.end,
  				       bus_max);
  
  	/* Map our Configuration Space windows */
  	if (!devm_request_mem_region(dev, pci->cfg.res.start,
  				     resource_size(&pci->cfg.res),
  				     "Configuration Space"))
  		return -ENOMEM;
  
  	bus_range = &pci->cfg.bus_range;
  	for (busn = bus_range->start; busn <= bus_range->end; ++busn) {
  		u32 idx = busn - bus_range->start;
  		u32 sz = 1 << pci->cfg.ops->bus_shift;
  
  		pci->cfg.win[idx] = devm_ioremap(dev,
  						 pci->cfg.res.start + busn * sz,
  						 sz);
  		if (!pci->cfg.win[idx])
  			return -ENOMEM;
  	}
  
  	/* Register bus resource */
  	pci_add_resource(&pci->resources, bus_range);
  	return 0;
  }
  
  static int gen_pci_setup(int nr, struct pci_sys_data *sys)
  {
  	struct gen_pci *pci = sys->private_data;
  	list_splice_init(&pci->resources, &sys->resources);
  	return 1;
  }
  
  static int gen_pci_probe(struct platform_device *pdev)
  {
  	int err;
  	const char *type;
  	const struct of_device_id *of_id;
  	const int *prop;
  	struct device *dev = &pdev->dev;
  	struct device_node *np = dev->of_node;
  	struct gen_pci *pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
  	struct hw_pci hw = {
  		.nr_controllers	= 1,
  		.private_data	= (void **)&pci,
  		.setup		= gen_pci_setup,
  		.map_irq	= of_irq_parse_and_map_pci,
  		.ops		= &gen_pci_ops,
  	};
  
  	if (!pci)
  		return -ENOMEM;
  
  	type = of_get_property(np, "device_type", NULL);
  	if (!type || strcmp(type, "pci")) {
  		dev_err(dev, "invalid \"device_type\" %s
  ", type);
  		return -EINVAL;
  	}
  
  	prop = of_get_property(of_chosen, "linux,pci-probe-only", NULL);
  	if (prop) {
  		if (*prop)
  			pci_add_flags(PCI_PROBE_ONLY);
  		else
  			pci_clear_flags(PCI_PROBE_ONLY);
  	}
  
  	of_id = of_match_node(gen_pci_of_match, np);
  	pci->cfg.ops = of_id->data;
  	pci->host.dev.parent = dev;
  	INIT_LIST_HEAD(&pci->host.windows);
  	INIT_LIST_HEAD(&pci->resources);
  
  	/* Parse our PCI ranges and request their resources */
  	err = gen_pci_parse_request_of_pci_ranges(pci);
  	if (err)
  		return err;
  
  	/* Parse and map our Configuration Space windows */
  	err = gen_pci_parse_map_cfg_windows(pci);
  	if (err) {
  		gen_pci_release_of_pci_ranges(pci);
  		return err;
  	}
  
  	pci_common_init_dev(dev, &hw);
  	return 0;
  }
  
  static struct platform_driver gen_pci_driver = {
  	.driver = {
  		.name = "pci-host-generic",
  		.owner = THIS_MODULE,
  		.of_match_table = gen_pci_of_match,
  	},
  	.probe = gen_pci_probe,
  };
  module_platform_driver(gen_pci_driver);
  
  MODULE_DESCRIPTION("Generic PCI host driver");
  MODULE_AUTHOR("Will Deacon <will.deacon@arm.com>");
  MODULE_LICENSE("GPLv2");