diff options
Diffstat (limited to 'drivers/char/agp/isoch.c')
| -rw-r--r-- | drivers/char/agp/isoch.c | 472 |
1 files changed, 472 insertions, 0 deletions
diff --git a/drivers/char/agp/isoch.c b/drivers/char/agp/isoch.c new file mode 100644 index 000000000..31c374b1b --- /dev/null +++ b/drivers/char/agp/isoch.c @@ -0,0 +1,472 @@ +// 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; + u8 mcapndx; + 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; + + mcapndx = cur->capndx; + + 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; + + mcapndx = cur->capndx; + + 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, arqsz; + 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; + + arqsz = (tstatus >> 13) & 0x7; + + /* + * 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; +} |