[PATCH v1 06/14] xen/arm: Add support for PCI ecam operations

[Rahul Singh <rahul.singh@arm.com>]

Add support for PCI ecam operations to access the PCI
configuration space.

Signed-off-by: Rahul Singh <rahul.singh@arm.com>
---
 xen/arch/arm/pci/Makefile           |  1 +
 xen/arch/arm/pci/ecam.c             | 63 +++++++++++++++++++++++++++++
 xen/arch/arm/pci/pci-access.c       | 53 ++++++++++++++++++++++++
 xen/arch/arm/pci/pci-host-common.c  | 13 +++++-
 xen/arch/arm/pci/pci-host-generic.c |  8 +++-
 xen/include/asm-arm/pci.h           | 32 +++++++++++++++
 6 files changed, 167 insertions(+), 3 deletions(-)
 create mode 100644 xen/arch/arm/pci/ecam.c

diff --git a/xen/arch/arm/pci/Makefile b/xen/arch/arm/pci/Makefile
index f3d97f859e..6f32fbbe67 100644
--- a/xen/arch/arm/pci/Makefile
+++ b/xen/arch/arm/pci/Makefile
@@ -2,3 +2,4 @@ obj-y += pci.o
 obj-y += pci-access.o
 obj-y += pci-host-generic.o
 obj-y += pci-host-common.o
+obj-y += ecam.o
diff --git a/xen/arch/arm/pci/ecam.c b/xen/arch/arm/pci/ecam.c
new file mode 100644
index 0000000000..91c691b41f
--- /dev/null
+++ b/xen/arch/arm/pci/ecam.c
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2021 Arm Ltd.
+ *
+ * Based on Linux drivers/pci/ecam.c
+ * 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.
+ *
+ * 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/>.
+ */
+
+#include <xen/pci.h>
+#include <xen/sched.h>
+
+/*
+ * Function to implement the pci_ops ->map_bus method.
+ */
+void __iomem *pci_ecam_map_bus(struct pci_host_bridge *bridge,
+                                      uint32_t sbdf, uint32_t where)
+{
+    const struct pci_config_window *cfg = bridge->sysdata;
+    unsigned int devfn_shift = cfg->ops->bus_shift - 8;
+    void __iomem *base;
+
+    pci_sbdf_t sbdf_t = (pci_sbdf_t) sbdf ;
+    unsigned int busn = sbdf_t.bus;
+
+    if ( busn < cfg->busn_start || busn > cfg->busn_end )
+        return NULL;
+
+    busn -= cfg->busn_start;
+    base = cfg->win + (busn << cfg->ops->bus_shift);
+
+    return base + (PCI_DEVFN(sbdf_t.dev, sbdf_t.fn) << devfn_shift) + where;
+}
+
+/* ECAM ops */
+const struct pci_ecam_ops pci_generic_ecam_ops = {
+    .bus_shift  = 20,
+    .pci_ops    = {
+        .map_bus                = pci_ecam_map_bus,
+        .read                   = pci_generic_config_read,
+        .write                  = pci_generic_config_write,
+    }
+};
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/pci/pci-access.c b/xen/arch/arm/pci/pci-access.c
index b938047c03..f39f6a3a38 100644
--- a/xen/arch/arm/pci/pci-access.c
+++ b/xen/arch/arm/pci/pci-access.c
@@ -15,6 +15,59 @@
  */
 
 #include <xen/pci.h>
+#include <asm/io.h>
+
+int pci_generic_config_read(struct pci_host_bridge *bridge, uint32_t sbdf,
+                            uint32_t reg, uint32_t len, uint32_t *value)
+{
+    void __iomem *addr = bridge->ops->map_bus(bridge, sbdf, reg);
+    if (!addr) {
+        *value = ~0;
+        return -ENODEV;
+    }
+
+    switch (len)
+    {
+    case 1:
+        *value = readb(addr);
+        break;
+    case 2:
+        *value = readw(addr);
+        break;
+    case 4:
+        *value = readl(addr);
+        break;
+    default:
+        BUG();
+    }
+
+    return 0;
+}
+
+int pci_generic_config_write(struct pci_host_bridge *bridge, uint32_t sbdf,
+                            uint32_t reg, uint32_t len, uint32_t value)
+{
+    void __iomem *addr = bridge->ops->map_bus(bridge, sbdf, reg);
+    if (!addr)
+        return -ENODEV;
+
+    switch (len)
+    {
+    case 1:
+        writeb(value, addr);
+        break;
+    case 2:
+        writew(value, addr);
+        break;
+    case 4:
+        writel(value, addr);
+        break;
+    default:
+        BUG();
+    }
+
+    return 0;
+}
 
 static uint32_t pci_config_read(pci_sbdf_t sbdf, unsigned int reg,
                                 unsigned int len)
diff --git a/xen/arch/arm/pci/pci-host-common.c b/xen/arch/arm/pci/pci-host-common.c
index 9dd9b02271..c582527e92 100644
--- a/xen/arch/arm/pci/pci-host-common.c
+++ b/xen/arch/arm/pci/pci-host-common.c
@@ -68,6 +68,7 @@ static void pci_ecam_free(struct pci_config_window *cfg)
 }
 
 static struct pci_config_window *gen_pci_init(struct dt_device_node *dev,
+                                              const struct pci_ecam_ops *ops,
                                               int ecam_reg_idx)
 {
     int err;
@@ -96,6 +97,7 @@ static struct pci_config_window *gen_pci_init(struct dt_device_node *dev,
 
     cfg->phys_addr = addr;
     cfg->size = size;
+    cfg->ops = ops;
 
     /*
      * On 64-bit systems, we do a single ioremap for the whole config space
@@ -111,6 +113,13 @@ static struct pci_config_window *gen_pci_init(struct dt_device_node *dev,
     printk("ECAM at [mem %lx-%lx] for [bus %x-%x] \n",cfg->phys_addr,
             cfg->phys_addr + cfg->size - 1, cfg->busn_start, cfg->busn_end);
 
+    if ( ops->init )
+    {
+        err = ops->init(cfg);
+        if (err)
+            goto err_exit;
+    }
+
     return cfg;
 
 err_exit_remap:
@@ -216,6 +225,7 @@ static int pci_bus_find_domain_nr(struct dt_device_node *dev)
 }
 
 int pci_host_common_probe(struct dt_device_node *dev,
+                          const struct pci_ecam_ops *ops,
                           int ecam_reg_idx)
 {
     struct pci_host_bridge *bridge;
@@ -227,7 +237,7 @@ int pci_host_common_probe(struct dt_device_node *dev,
         return -ENOMEM;
 
     /* Parse and map our Configuration Space windows */
-    cfg = gen_pci_init(dev, ecam_reg_idx);
+    cfg = gen_pci_init(dev, ops, ecam_reg_idx);
     if ( !cfg )
     {
         err = -ENOMEM;
@@ -236,6 +246,7 @@ int pci_host_common_probe(struct dt_device_node *dev,
 
     bridge->dt_node = dev;
     bridge->sysdata = cfg;
+    bridge->ops = &ops->pci_ops;
     bridge->bus_start = cfg->busn_start;
     bridge->bus_end = cfg->busn_end;
 
diff --git a/xen/arch/arm/pci/pci-host-generic.c b/xen/arch/arm/pci/pci-host-generic.c
index 13d0f7f999..2d652e8910 100644
--- a/xen/arch/arm/pci/pci-host-generic.c
+++ b/xen/arch/arm/pci/pci-host-generic.c
@@ -23,20 +23,24 @@
 #include <asm/pci.h>
 
 static const struct dt_device_match gen_pci_dt_match[] = {
-    { .compatible = "pci-host-ecam-generic" },
+    { .compatible = "pci-host-ecam-generic",
+      .data =       &pci_generic_ecam_ops },
+
     { },
 };
 
 static int gen_pci_dt_init(struct dt_device_node *dev, const void *data)
 {
     const struct dt_device_match *of_id;
+    const struct pci_ecam_ops *ops;
 
     of_id = dt_match_node(gen_pci_dt_match, dev->dev.of_node);
+    ops = (struct pci_ecam_ops *) of_id->data;
 
     printk(XENLOG_INFO "Found PCI host bridge %s compatible:%s \n",
            dt_node_full_name(dev), of_id->compatible);
 
-    return pci_host_common_probe(dev, 0);
+    return pci_host_common_probe(dev, ops, 0);
 }
 
 DT_DEVICE_START(pci_gen, "PCI HOST GENERIC", DEVICE_PCI)
diff --git a/xen/include/asm-arm/pci.h b/xen/include/asm-arm/pci.h
index 58a51e724e..22866244d2 100644
--- a/xen/include/asm-arm/pci.h
+++ b/xen/include/asm-arm/pci.h
@@ -37,6 +37,7 @@ struct pci_config_window {
     uint8_t         busn_start;
     uint8_t         busn_end;
     void __iomem    *win;
+    const struct    pci_ecam_ops *ops;
 };
 
 /*
@@ -50,10 +51,41 @@ struct pci_host_bridge {
     u8 bus_start;                    /* Bus start of this bridge. */
     u8 bus_end;                      /* Bus end of this bridge. */
     void *sysdata;                   /* Pointer to the config space window*/
+    const struct pci_ops *ops;
 };
 
+struct pci_ops {
+    void __iomem *(*map_bus)(struct pci_host_bridge *bridge, uint32_t sbdf,
+                             uint32_t offset);
+    int (*read)(struct pci_host_bridge *bridge, uint32_t sbdf,
+                uint32_t reg, uint32_t len, uint32_t *value);
+    int (*write)(struct pci_host_bridge *bridge, uint32_t sbdf,
+                 uint32_t reg, uint32_t len, uint32_t value);
+};
+
+/*
+ * struct to hold pci ops and bus shift of the config window
+ * for a PCI controller.
+ */
+struct pci_ecam_ops {
+    unsigned int            bus_shift;
+    struct pci_ops          pci_ops;
+    int (*init)(struct pci_config_window *);
+};
+
+/* Default ECAM ops */
+extern const struct pci_ecam_ops pci_generic_ecam_ops;
+
 int pci_host_common_probe(struct dt_device_node *dev,
+                          const struct pci_ecam_ops *ops,
                           int ecam_reg_idx);
+int pci_generic_config_read(struct pci_host_bridge *bridge, uint32_t sbdf,
+                            uint32_t reg, uint32_t len, uint32_t *value);
+int pci_generic_config_write(struct pci_host_bridge *bridge, uint32_t sbdf,
+                            uint32_t reg, uint32_t len, uint32_t value);
+void __iomem *pci_ecam_map_bus(struct pci_host_bridge *bridge,
+                               uint32_t sbdf, uint32_t where);
+
 #else   /*!CONFIG_HAS_PCI*/
 
 struct arch_pci_dev { };
-- 
2.17.1