[dpdk-dev] [RFC] PCI config access for drivers

[Stephen Hemminger]

Some drivers need ability to access PCI config (for example for power
management). This adds an abstraction to do this; only implemented
on Linux, but should be possible on BSD.

Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>

--- a/lib/librte_eal/common/include/rte_pci.h   2014-06-24 09:20:05.651993525 
-0700
+++ b/lib/librte_eal/common/include/rte_pci.h   2014-06-24 09:25:42.150616572 
-0700
@@ -151,6 +151,7 @@ struct rte_pci_device {
        const struct rte_pci_driver *driver;    /**< Associated driver */
        uint16_t max_vfs;                       /**< sriov enable if not zero */
        int numa_node;                          /**< NUMA node connection */
+       int config_fd;                          /**< PCI config access */
        struct rte_devargs *devargs;            /**< Device user arguments */
 };

@@ -298,6 +299,34 @@ void rte_eal_pci_register(struct rte_pci
  */
 void rte_eal_pci_unregister(struct rte_pci_driver *driver);

+/**
+ * Read PCI config space.
+ *
+ * @param device
+ *   A pointer to a rte_pci_device structure describing the device
+ *   to use
+ * @param buf
+ *   A data buffer where the bytes should be read into
+ * @param size
+ *   The length of the data buffer.
+ */
+int rte_eal_pci_read_config(const struct rte_pci_device *device,
+                           void *buf, size_t len, off_t offset);
+
+/**
+ * Write PCI config space.
+ *
+ * @param device
+ *   A pointer to a rte_pci_device structure describing the device
+ *   to use
+ * @param buf
+ *   A data buffer containing the bytes should be written
+ * @param size
+ *   The length of the data buffer.
+ */
+int rte_eal_pci_write_config(const struct rte_pci_device *device,
+                            const void *buf, size_t len, off_t offset);
+
 #ifdef __cplusplus
 }
 #endif
--- a/lib/librte_eal/linuxapp/eal/eal_pci.c     2014-06-24 09:20:05.651993525 
-0700
+++ b/lib/librte_eal/linuxapp/eal/eal_pci.c     2014-06-24 09:20:05.651993525 
-0700
@@ -219,6 +219,7 @@ pci_scan_one(const char *dirname, uint16
        dev->addr.bus = bus;
        dev->addr.devid = devid;
        dev->addr.function = function;
+       dev->config_fd = -1;

        /* get vendor id */
        snprintf(filename, sizeof(filename), "%s/vendor", dirname);
@@ -578,6 +579,20 @@ rte_eal_pci_probe_one_driver(struct rte_
        return 1;
 }

+/* Read PCI config space. */
+int rte_eal_pci_read_config(const struct rte_pci_device *device,
+                           void *buf, size_t len, off_t offset)
+{
+       return pread(device->config_fd, buf, len, offset);
+}
+
+/* Write PCI config space. */
+int rte_eal_pci_write_config(const struct rte_pci_device *device,
+                            const void *buf, size_t len, off_t offset)
+{
+       return pwrite(device->config_fd, buf, len, offset);
+}
+
 /* Init the PCI EAL subsystem */
 int
 rte_eal_pci_init(void)
--- a/lib/librte_eal/linuxapp/eal/eal_pci_uio.c 2014-06-24 08:35:31.832146544 
-0700
+++ b/lib/librte_eal/linuxapp/eal/eal_pci_uio.c 2014-06-24 09:37:44.892296443 
-0700
@@ -280,6 +280,7 @@ pci_uio_map_resource(struct rte_pci_devi
        int i, j;
        char dirname[PATH_MAX];
        char devname[PATH_MAX]; /* contains the /dev/uioX */
+       char cfgname[PATH_MAX];
        void *mapaddr;
        int uio_num;
        uint64_t phaddr;
@@ -326,11 +327,23 @@ pci_uio_map_resource(struct rte_pci_devi
        snprintf(uio_res->path, sizeof(uio_res->path), "%s", devname);
        memcpy(&uio_res->pci_addr, &dev->addr, sizeof(uio_res->pci_addr));

+       /* Open fd for access to PCI config */
+       snprintf(cfgname, sizeof(cfgname),
+                "%s/device/config", dirname);
+       dev->config_fd = open(cfgname, O_RDWR);
+       if (dev->config_fd < 0) {
+               RTE_LOG(ERR, EAL, "%s(): cannot open %s: %s\n",
+                       __func__, cfgname, strerror(errno));
+               rte_free(uio_res);
+               return -1;
+       }
+
        /* collect info about device mappings */
        nb_maps = pci_uio_get_mappings(dirname, uio_res->maps,
                                       RTE_DIM(uio_res->maps));
        if (nb_maps < 0) {
                rte_free(uio_res);
+               close(dev->config_fd);
                return nb_maps;
        }

@@ -379,6 +392,7 @@ pci_uio_map_resource(struct rte_pci_devi

                        if (fail) {
                                rte_free(uio_res);
+                               close(dev->config_fd);
                                close(fd);
                                return -1;
                        }