[PATCH v2 2/4] PCI: Provide common functions for ECAM mapping

[Jayachandran C <jchandra@broadcom.com>]

Add config option PCI_GENERIC_ECAM and file drivers/pci/ecam.c to
provide generic functions for accessing memory mapped PCI config space.

The API is defined in drivers/pci/ecam.h and is written to replace the
API in drivers/pci/host/pci-host-common.h. The file defines a new
'struct pci_config_window' to hold the information related to a PCI
config area and its mapping. This structure is expected to be used as
sysdata for controllers that have ECAM based mapping.

Helper functions are provided to setup the mapping, free the mapping
and to implement the map_bus method in 'struct pci_ops'

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
---
 drivers/pci/Kconfig  |   3 ++
 drivers/pci/Makefile |   2 +
 drivers/pci/ecam.c   | 130 +++++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/pci/ecam.h   |  58 +++++++++++++++++++++++
 4 files changed, 193 insertions(+)
 create mode 100644 drivers/pci/ecam.c
 create mode 100644 drivers/pci/ecam.h

diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index 209292e..e930d62 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -83,6 +83,9 @@ config HT_IRQ
 config PCI_ATS
 	bool
 
+config PCI_GENERIC_ECAM
+	bool
+
 config PCI_IOV
 	bool "PCI IOV support"
 	depends on PCI
diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
index 2154092..810aec8 100644
--- a/drivers/pci/Makefile
+++ b/drivers/pci/Makefile
@@ -55,6 +55,8 @@ obj-$(CONFIG_PCI_SYSCALL) += syscall.o
 
 obj-$(CONFIG_PCI_STUB) += pci-stub.o
 
+obj-$(CONFIG_PCI_GENERIC_ECAM) += ecam.o
+
 obj-$(CONFIG_XEN_PCIDEV_FRONTEND) += xen-pcifront.o
 
 obj-$(CONFIG_OF) += of.o
diff --git a/drivers/pci/ecam.c b/drivers/pci/ecam.c
new file mode 100644
index 00000000..798f0b7
--- /dev/null
+++ b/drivers/pci/ecam.c
@@ -0,0 +1,130 @@
+/*
+ * Copyright 2016 Broadcom
+ *
+ * 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 (the "GPL").
+ *
+ * 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 version 2 (GPLv2) for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 (GPLv2) along with this source code.
+ */
+
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+
+#include "ecam.h"
+
+/*
+ * On 64 bit systems, we do a single ioremap for the whole config space
+ * since we have enough virtual address range available. On 32 bit, do an
+ * ioremap per bus.
+ */
+static const bool per_bus_mapping = !config_enabled(CONFIG_64BIT);
+
+/*
+ * Create a PCI config space window
+ *  - reserve mem region
+ *  - alloc struct pci_config_window with space for all mappings
+ *  - ioremap the config space
+ */
+struct pci_config_window *pci_generic_ecam_create(struct device *dev,
+				phys_addr_t addr, u8 bus_start, u8 bus_end,
+				struct pci_generic_ecam_ops *ops)
+{
+	struct pci_config_window *cfg;
+	unsigned int bus_shift, bus_range, bsz, mapsz;
+	int i, nidx;
+
+	if (bus_end < bus_start)
+		return ERR_PTR(-EINVAL);
+
+	bus_shift = ops->bus_shift;
+	bus_range = bus_end - bus_start + 1;
+	bsz = 1 << bus_shift;
+	nidx = per_bus_mapping ? bus_range : 1;
+	mapsz = per_bus_mapping ? bsz : bus_range * bsz;
+	cfg = kzalloc(sizeof(*cfg) + nidx * sizeof(cfg->win[0]), GFP_KERNEL);
+	if (!cfg)
+		return ERR_PTR(-ENOMEM);
+
+	cfg->bus_start = bus_start;
+	cfg->bus_end = bus_end;
+	cfg->ops = ops;
+
+	if (!request_mem_region(addr, bus_range * bsz, "Configuration Space"))
+		goto err_exit;
+
+	/* cfgaddr has to be set after request_mem_region */
+	cfg->cfgaddr = addr;
+
+	for (i = 0; i < nidx; i++) {
+		cfg->win[i] = ioremap(addr + i * mapsz, mapsz);
+		if (!cfg->win[i])
+			goto err_exit;
+	}
+	return cfg;
+
+err_exit:
+	pci_generic_ecam_free(cfg);
+	return ERR_PTR(-ENOMEM);
+}
+
+/*
+ * Free a config space mapping
+ */
+void pci_generic_ecam_free(struct pci_config_window *cfg)
+{
+	unsigned int bus_range;
+	int i, nidx;
+
+	bus_range = cfg->bus_end - cfg->bus_start + 1;
+	nidx = per_bus_mapping ? bus_range : 1;
+	for (i = 0; i < nidx; i++)
+		if (cfg->win[i])
+			iounmap(cfg->win[i]);
+	if (cfg->cfgaddr)
+		release_mem_region(cfg->cfgaddr,
+				   bus_range << cfg->ops->bus_shift);
+	kfree(cfg);
+}
+
+/*
+ * Function to implement the pci_ops ->map_bus method
+ */
+void __iomem *pci_generic_ecam_map_bus(struct pci_bus *bus, unsigned int devfn,
+				       int where)
+{
+	struct pci_config_window *cfg = bus->sysdata;
+	unsigned int devfn_shift = cfg->ops->bus_shift - 8;
+	unsigned int busn = bus->number;
+	void __iomem *base;
+
+	if (busn < cfg->bus_start || busn > cfg->bus_end)
+		return NULL;
+
+	busn -= cfg->bus_start;
+	if (per_bus_mapping)
+		base = cfg->win[busn];
+	else
+		base = cfg->win[0] + (busn << cfg->ops->bus_shift);
+	return base + (devfn << devfn_shift) + where;
+}
+
+/* default ECAM ops */
+struct pci_generic_ecam_ops pci_generic_ecam_default_ops = {
+	.bus_shift	= 20,
+	.ops		= {
+		.map_bus	= pci_generic_ecam_map_bus,
+		.read		= pci_generic_config_read,
+		.write		= pci_generic_config_write,
+	}
+};
diff --git a/drivers/pci/ecam.h b/drivers/pci/ecam.h
new file mode 100644
index 00000000..dda8c50
--- /dev/null
+++ b/drivers/pci/ecam.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2016 Broadcom
+ *
+ * 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 (the "GPL").
+ *
+ * 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 version 2 (GPLv2) for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 (GPLv2) along with this source code.
+ */
+#ifndef DRIVERS_PCI_ECAM_H
+#define DRIVERS_PCI_ECAM_H
+
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+
+/*
+ * struct to hold pci ops and bus shift of the config window
+ * for a PCI controller.
+ */
+struct pci_generic_ecam_ops {
+	unsigned int			bus_shift;
+	struct pci_ops			ops;
+};
+
+/*
+ * struct to hold the mappings of a config space window. This
+ * will be allocated with enough entries in win[] to hold all
+ * the mappings for the bus range.
+ */
+struct pci_config_window {
+	phys_addr_t			cfgaddr;
+	u16				domain;
+	u8				bus_start;
+	u8				bus_end;
+	void				*priv;
+	struct pci_generic_ecam_ops	*ops;
+	void __iomem			*win[0];
+};
+
+/* create and free for pci_config_window */
+struct pci_config_window *pci_generic_ecam_create(struct device *dev,
+				phys_addr_t addr, u8 bus_start, u8 bus_end,
+				struct pci_generic_ecam_ops *ops);
+void pci_generic_ecam_free(struct pci_config_window *cfg);
+
+/* map_bus when ->sysdata is an instance of pci_config_window */
+void __iomem *pci_generic_ecam_map_bus(struct pci_bus *bus, unsigned int devfn,
+				       int where);
+/* default ECAM ops, bus shift 20, generic read and write */
+extern struct pci_generic_ecam_ops pci_generic_ecam_default_ops;
+
+#endif
-- 
1.9.1