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-rw-r--r--drivers/char/agp/isoch.c465
1 files changed, 465 insertions, 0 deletions
diff --git a/drivers/char/agp/isoch.c b/drivers/char/agp/isoch.c
new file mode 100644
index 000000000..7ecf20a6d
--- /dev/null
+++ b/drivers/char/agp/isoch.c
@@ -0,0 +1,465 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Setup routines for AGP 3.5 compliant bridges.
+ */
+
+#include <linux/list.h>
+#include <linux/pci.h>
+#include <linux/agp_backend.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "agp.h"
+
+/* Generic AGP 3.5 enabling routines */
+
+struct agp_3_5_dev {
+ struct list_head list;
+ u8 capndx;
+ u32 maxbw;
+ struct pci_dev *dev;
+};
+
+static void agp_3_5_dev_list_insert(struct list_head *head, struct list_head *new)
+{
+ struct agp_3_5_dev *cur, *n = list_entry(new, struct agp_3_5_dev, list);
+ struct list_head *pos;
+
+ list_for_each(pos, head) {
+ cur = list_entry(pos, struct agp_3_5_dev, list);
+ if (cur->maxbw > n->maxbw)
+ break;
+ }
+ list_add_tail(new, pos);
+}
+
+static void agp_3_5_dev_list_sort(struct agp_3_5_dev *list, unsigned int ndevs)
+{
+ struct agp_3_5_dev *cur;
+ struct pci_dev *dev;
+ struct list_head *pos, *tmp, *head = &list->list, *start = head->next;
+ u32 nistat;
+
+ INIT_LIST_HEAD(head);
+
+ for (pos=start; pos!=head; ) {
+ cur = list_entry(pos, struct agp_3_5_dev, list);
+ dev = cur->dev;
+
+ pci_read_config_dword(dev, cur->capndx+AGPNISTAT, &nistat);
+ cur->maxbw = (nistat >> 16) & 0xff;
+
+ tmp = pos;
+ pos = pos->next;
+ agp_3_5_dev_list_insert(head, tmp);
+ }
+}
+
+/*
+ * Initialize all isochronous transfer parameters for an AGP 3.0
+ * node (i.e. a host bridge in combination with the adapters
+ * lying behind it...)
+ */
+
+static int agp_3_5_isochronous_node_enable(struct agp_bridge_data *bridge,
+ struct agp_3_5_dev *dev_list, unsigned int ndevs)
+{
+ /*
+ * Convenience structure to make the calculations clearer
+ * here. The field names come straight from the AGP 3.0 spec.
+ */
+ struct isoch_data {
+ u32 maxbw;
+ u32 n;
+ u32 y;
+ u32 l;
+ u32 rq;
+ struct agp_3_5_dev *dev;
+ };
+
+ struct pci_dev *td = bridge->dev, *dev;
+ struct list_head *head = &dev_list->list, *pos;
+ struct agp_3_5_dev *cur;
+ struct isoch_data *master, target;
+ unsigned int cdev = 0;
+ u32 mnistat, tnistat, tstatus, mcmd;
+ u16 tnicmd, mnicmd;
+ u32 tot_bw = 0, tot_n = 0, tot_rq = 0, y_max, rq_isoch, rq_async;
+ u32 step, rem, rem_isoch, rem_async;
+ int ret = 0;
+
+ /*
+ * We'll work with an array of isoch_data's (one for each
+ * device in dev_list) throughout this function.
+ */
+ master = kmalloc_array(ndevs, sizeof(*master), GFP_KERNEL);
+ if (master == NULL) {
+ ret = -ENOMEM;
+ goto get_out;
+ }
+
+ /*
+ * Sort the device list by maxbw. We need to do this because the
+ * spec suggests that the devices with the smallest requirements
+ * have their resources allocated first, with all remaining resources
+ * falling to the device with the largest requirement.
+ *
+ * We don't exactly do this, we divide target resources by ndevs
+ * and split them amongst the AGP 3.0 devices. The remainder of such
+ * division operations are dropped on the last device, sort of like
+ * the spec mentions it should be done.
+ *
+ * We can't do this sort when we initially construct the dev_list
+ * because we don't know until this function whether isochronous
+ * transfers are enabled and consequently whether maxbw will mean
+ * anything.
+ */
+ agp_3_5_dev_list_sort(dev_list, ndevs);
+
+ pci_read_config_dword(td, bridge->capndx+AGPNISTAT, &tnistat);
+ pci_read_config_dword(td, bridge->capndx+AGPSTAT, &tstatus);
+
+ /* Extract power-on defaults from the target */
+ target.maxbw = (tnistat >> 16) & 0xff;
+ target.n = (tnistat >> 8) & 0xff;
+ target.y = (tnistat >> 6) & 0x3;
+ target.l = (tnistat >> 3) & 0x7;
+ target.rq = (tstatus >> 24) & 0xff;
+
+ y_max = target.y;
+
+ /*
+ * Extract power-on defaults for each device in dev_list. Along
+ * the way, calculate the total isochronous bandwidth required
+ * by these devices and the largest requested payload size.
+ */
+ list_for_each(pos, head) {
+ cur = list_entry(pos, struct agp_3_5_dev, list);
+ dev = cur->dev;
+
+ pci_read_config_dword(dev, cur->capndx+AGPNISTAT, &mnistat);
+
+ master[cdev].maxbw = (mnistat >> 16) & 0xff;
+ master[cdev].n = (mnistat >> 8) & 0xff;
+ master[cdev].y = (mnistat >> 6) & 0x3;
+ master[cdev].dev = cur;
+
+ tot_bw += master[cdev].maxbw;
+ y_max = max(y_max, master[cdev].y);
+
+ cdev++;
+ }
+
+ /* Check if this configuration has any chance of working */
+ if (tot_bw > target.maxbw) {
+ dev_err(&td->dev, "isochronous bandwidth required "
+ "by AGP 3.0 devices exceeds that which is supported by "
+ "the AGP 3.0 bridge!\n");
+ ret = -ENODEV;
+ goto free_and_exit;
+ }
+
+ target.y = y_max;
+
+ /*
+ * Write the calculated payload size into the target's NICMD
+ * register. Doing this directly effects the ISOCH_N value
+ * in the target's NISTAT register, so we need to do this now
+ * to get an accurate value for ISOCH_N later.
+ */
+ pci_read_config_word(td, bridge->capndx+AGPNICMD, &tnicmd);
+ tnicmd &= ~(0x3 << 6);
+ tnicmd |= target.y << 6;
+ pci_write_config_word(td, bridge->capndx+AGPNICMD, tnicmd);
+
+ /* Reread the target's ISOCH_N */
+ pci_read_config_dword(td, bridge->capndx+AGPNISTAT, &tnistat);
+ target.n = (tnistat >> 8) & 0xff;
+
+ /* Calculate the minimum ISOCH_N needed by each master */
+ for (cdev=0; cdev<ndevs; cdev++) {
+ master[cdev].y = target.y;
+ master[cdev].n = master[cdev].maxbw / (master[cdev].y + 1);
+
+ tot_n += master[cdev].n;
+ }
+
+ /* Exit if the minimal ISOCH_N allocation among the masters is more
+ * than the target can handle. */
+ if (tot_n > target.n) {
+ dev_err(&td->dev, "number of isochronous "
+ "transactions per period required by AGP 3.0 devices "
+ "exceeds that which is supported by the AGP 3.0 "
+ "bridge!\n");
+ ret = -ENODEV;
+ goto free_and_exit;
+ }
+
+ /* Calculate left over ISOCH_N capability in the target. We'll give
+ * this to the hungriest device (as per the spec) */
+ rem = target.n - tot_n;
+
+ /*
+ * Calculate the minimum isochronous RQ depth needed by each master.
+ * Along the way, distribute the extra ISOCH_N capability calculated
+ * above.
+ */
+ for (cdev=0; cdev<ndevs; cdev++) {
+ /*
+ * This is a little subtle. If ISOCH_Y > 64B, then ISOCH_Y
+ * byte isochronous writes will be broken into 64B pieces.
+ * This means we need to budget more RQ depth to account for
+ * these kind of writes (each isochronous write is actually
+ * many writes on the AGP bus).
+ */
+ master[cdev].rq = master[cdev].n;
+ if (master[cdev].y > 0x1)
+ master[cdev].rq *= (1 << (master[cdev].y - 1));
+
+ tot_rq += master[cdev].rq;
+ }
+ master[ndevs-1].n += rem;
+
+ /* Figure the number of isochronous and asynchronous RQ slots the
+ * target is providing. */
+ rq_isoch = (target.y > 0x1) ? target.n * (1 << (target.y - 1)) : target.n;
+ rq_async = target.rq - rq_isoch;
+
+ /* Exit if the minimal RQ needs of the masters exceeds what the target
+ * can provide. */
+ if (tot_rq > rq_isoch) {
+ dev_err(&td->dev, "number of request queue slots "
+ "required by the isochronous bandwidth requested by "
+ "AGP 3.0 devices exceeds the number provided by the "
+ "AGP 3.0 bridge!\n");
+ ret = -ENODEV;
+ goto free_and_exit;
+ }
+
+ /* Calculate asynchronous RQ capability in the target (per master) as
+ * well as the total number of leftover isochronous RQ slots. */
+ step = rq_async / ndevs;
+ rem_async = step + (rq_async % ndevs);
+ rem_isoch = rq_isoch - tot_rq;
+
+ /* Distribute the extra RQ slots calculated above and write our
+ * isochronous settings out to the actual devices. */
+ for (cdev=0; cdev<ndevs; cdev++) {
+ cur = master[cdev].dev;
+ dev = cur->dev;
+
+ master[cdev].rq += (cdev == ndevs - 1)
+ ? (rem_async + rem_isoch) : step;
+
+ pci_read_config_word(dev, cur->capndx+AGPNICMD, &mnicmd);
+ pci_read_config_dword(dev, cur->capndx+AGPCMD, &mcmd);
+
+ mnicmd &= ~(0xff << 8);
+ mnicmd &= ~(0x3 << 6);
+ mcmd &= ~(0xff << 24);
+
+ mnicmd |= master[cdev].n << 8;
+ mnicmd |= master[cdev].y << 6;
+ mcmd |= master[cdev].rq << 24;
+
+ pci_write_config_dword(dev, cur->capndx+AGPCMD, mcmd);
+ pci_write_config_word(dev, cur->capndx+AGPNICMD, mnicmd);
+ }
+
+free_and_exit:
+ kfree(master);
+
+get_out:
+ return ret;
+}
+
+/*
+ * This function basically allocates request queue slots among the
+ * AGP 3.0 systems in nonisochronous nodes. The algorithm is
+ * pretty stupid, divide the total number of RQ slots provided by the
+ * target by ndevs. Distribute this many slots to each AGP 3.0 device,
+ * giving any left over slots to the last device in dev_list.
+ */
+static void agp_3_5_nonisochronous_node_enable(struct agp_bridge_data *bridge,
+ struct agp_3_5_dev *dev_list, unsigned int ndevs)
+{
+ struct agp_3_5_dev *cur;
+ struct list_head *head = &dev_list->list, *pos;
+ u32 tstatus, mcmd;
+ u32 trq, mrq, rem;
+ unsigned int cdev = 0;
+
+ pci_read_config_dword(bridge->dev, bridge->capndx+AGPSTAT, &tstatus);
+
+ trq = (tstatus >> 24) & 0xff;
+ mrq = trq / ndevs;
+
+ rem = mrq + (trq % ndevs);
+
+ for (pos=head->next; cdev<ndevs; cdev++, pos=pos->next) {
+ cur = list_entry(pos, struct agp_3_5_dev, list);
+
+ pci_read_config_dword(cur->dev, cur->capndx+AGPCMD, &mcmd);
+ mcmd &= ~(0xff << 24);
+ mcmd |= ((cdev == ndevs - 1) ? rem : mrq) << 24;
+ pci_write_config_dword(cur->dev, cur->capndx+AGPCMD, mcmd);
+ }
+}
+
+/*
+ * Fully configure and enable an AGP 3.0 host bridge and all the devices
+ * lying behind it.
+ */
+int agp_3_5_enable(struct agp_bridge_data *bridge)
+{
+ struct pci_dev *td = bridge->dev, *dev = NULL;
+ u8 mcapndx;
+ u32 isoch;
+ u32 tstatus, mstatus, ncapid;
+ u32 mmajor;
+ u16 mpstat;
+ struct agp_3_5_dev *dev_list, *cur;
+ struct list_head *head, *pos;
+ unsigned int ndevs = 0;
+ int ret = 0;
+
+ /* Extract some power-on defaults from the target */
+ pci_read_config_dword(td, bridge->capndx+AGPSTAT, &tstatus);
+ isoch = (tstatus >> 17) & 0x1;
+ if (isoch == 0) /* isoch xfers not available, bail out. */
+ return -ENODEV;
+
+ /*
+ * Allocate a head for our AGP 3.5 device list
+ * (multiple AGP v3 devices are allowed behind a single bridge).
+ */
+ if ((dev_list = kmalloc(sizeof(*dev_list), GFP_KERNEL)) == NULL) {
+ ret = -ENOMEM;
+ goto get_out;
+ }
+ head = &dev_list->list;
+ INIT_LIST_HEAD(head);
+
+ /* Find all AGP devices, and add them to dev_list. */
+ for_each_pci_dev(dev) {
+ mcapndx = pci_find_capability(dev, PCI_CAP_ID_AGP);
+ if (mcapndx == 0)
+ continue;
+
+ switch ((dev->class >>8) & 0xff00) {
+ case 0x0600: /* Bridge */
+ /* Skip bridges. We should call this function for each one. */
+ continue;
+
+ case 0x0001: /* Unclassified device */
+ /* Don't know what this is, but log it for investigation. */
+ if (mcapndx != 0) {
+ dev_info(&td->dev, "wacky, found unclassified AGP device %s [%04x/%04x]\n",
+ pci_name(dev),
+ dev->vendor, dev->device);
+ }
+ continue;
+
+ case 0x0300: /* Display controller */
+ case 0x0400: /* Multimedia controller */
+ if ((cur = kmalloc(sizeof(*cur), GFP_KERNEL)) == NULL) {
+ ret = -ENOMEM;
+ goto free_and_exit;
+ }
+ cur->dev = dev;
+
+ pos = &cur->list;
+ list_add(pos, head);
+ ndevs++;
+ continue;
+
+ default:
+ continue;
+ }
+ }
+
+ /*
+ * Take an initial pass through the devices lying behind our host
+ * bridge. Make sure each one is actually an AGP 3.0 device, otherwise
+ * exit with an error message. Along the way store the AGP 3.0
+ * cap_ptr for each device
+ */
+ list_for_each(pos, head) {
+ cur = list_entry(pos, struct agp_3_5_dev, list);
+ dev = cur->dev;
+
+ pci_read_config_word(dev, PCI_STATUS, &mpstat);
+ if ((mpstat & PCI_STATUS_CAP_LIST) == 0)
+ continue;
+
+ pci_read_config_byte(dev, PCI_CAPABILITY_LIST, &mcapndx);
+ if (mcapndx != 0) {
+ do {
+ pci_read_config_dword(dev, mcapndx, &ncapid);
+ if ((ncapid & 0xff) != 2)
+ mcapndx = (ncapid >> 8) & 0xff;
+ }
+ while (((ncapid & 0xff) != 2) && (mcapndx != 0));
+ }
+
+ if (mcapndx == 0) {
+ dev_err(&td->dev, "woah! Non-AGP device %s on "
+ "secondary bus of AGP 3.5 bridge!\n",
+ pci_name(dev));
+ ret = -ENODEV;
+ goto free_and_exit;
+ }
+
+ mmajor = (ncapid >> AGP_MAJOR_VERSION_SHIFT) & 0xf;
+ if (mmajor < 3) {
+ dev_err(&td->dev, "woah! AGP 2.0 device %s on "
+ "secondary bus of AGP 3.5 bridge operating "
+ "with AGP 3.0 electricals!\n", pci_name(dev));
+ ret = -ENODEV;
+ goto free_and_exit;
+ }
+
+ cur->capndx = mcapndx;
+
+ pci_read_config_dword(dev, cur->capndx+AGPSTAT, &mstatus);
+
+ if (((mstatus >> 3) & 0x1) == 0) {
+ dev_err(&td->dev, "woah! AGP 3.x device %s not "
+ "operating in AGP 3.x mode on secondary bus "
+ "of AGP 3.5 bridge operating with AGP 3.0 "
+ "electricals!\n", pci_name(dev));
+ ret = -ENODEV;
+ goto free_and_exit;
+ }
+ }
+
+ /*
+ * Call functions to divide target resources amongst the AGP 3.0
+ * masters. This process is dramatically different depending on
+ * whether isochronous transfers are supported.
+ */
+ if (isoch) {
+ ret = agp_3_5_isochronous_node_enable(bridge, dev_list, ndevs);
+ if (ret) {
+ dev_info(&td->dev, "something bad happened setting "
+ "up isochronous xfers; falling back to "
+ "non-isochronous xfer mode\n");
+ } else {
+ goto free_and_exit;
+ }
+ }
+ agp_3_5_nonisochronous_node_enable(bridge, dev_list, ndevs);
+
+free_and_exit:
+ /* Be sure to free the dev_list */
+ for (pos=head->next; pos!=head; ) {
+ cur = list_entry(pos, struct agp_3_5_dev, list);
+
+ pos = pos->next;
+ kfree(cur);
+ }
+ kfree(dev_list);
+
+get_out:
+ return ret;
+}
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