[deliverable/linux.git] / drivers / char / agp / isoch.c

/*
 * 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.
	 */
	if ((master = kmalloc(ndevs * sizeof(*master), GFP_KERNEL)) == 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) {
		printk(KERN_ERR PFX "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) {
		printk(KERN_ERR PFX "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;

		if (cdev == ndevs-1)
			master[cdev].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) {
		printk(KERN_ERR PFX "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) {
					printk (KERN_INFO PFX "Wacky, found unclassified AGP device. %x:%x\n",
						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) {
			printk(KERN_ERR PFX "woah!  Non-AGP device "
				"found on the secondary bus of an AGP 3.5 bridge!\n");
			ret = -ENODEV;
			goto free_and_exit;
		}

		mmajor = (ncapid >> AGP_MAJOR_VERSION_SHIFT) & 0xf;
		if (mmajor < 3) {
			printk(KERN_ERR PFX "woah!  AGP 2.0 device "
				"found on the secondary bus of an AGP 3.5 "
				"bridge operating with AGP 3.0 electricals!\n");
			ret = -ENODEV;
			goto free_and_exit;
		}

		cur->capndx = mcapndx;

		pci_read_config_dword(dev, cur->capndx+AGPSTAT, &mstatus);

		if (((mstatus >> 3) & 0x1) == 0) {
			printk(KERN_ERR PFX "woah!  AGP 3.x device "
				"not operating in AGP 3.x mode found on the "
				"secondary bus of an AGP 3.5 bridge operating "
				"with AGP 3.0 electricals!\n");
			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) {
			printk(KERN_INFO PFX "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;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Setup routines for AGP 3.5 compliant bridges.
	3	*/
	4
	5	#include <linux/list.h>
	6	#include <linux/pci.h>
	7	#include <linux/agp_backend.h>
	8	#include <linux/module.h>
4e57b681	9	#include <linux/slab.h>
1da177e4 LT	10
	11	#include "agp.h"
	12
	13	/* Generic AGP 3.5 enabling routines */
	14
	15	struct agp_3_5_dev {
	16	struct list_head list;
	17	u8 capndx;
	18	u32 maxbw;
	19	struct pci_dev *dev;
	20	};
	21
	22	static void agp_3_5_dev_list_insert(struct list_head head, struct list_head new)
	23	{
	24	struct agp_3_5_dev cur, n = list_entry(new, struct agp_3_5_dev, list);
	25	struct list_head *pos;
	26
	27	list_for_each(pos, head) {
	28	cur = list_entry(pos, struct agp_3_5_dev, list);
	29	if(cur->maxbw > n->maxbw)
	30	break;
	31	}
	32	list_add_tail(new, pos);
	33	}
	34
	35	static void agp_3_5_dev_list_sort(struct agp_3_5_dev *list, unsigned int ndevs)
	36	{
	37	struct agp_3_5_dev *cur;
	38	struct pci_dev *dev;
	39	struct list_head pos, tmp, head = &list->list, start = head->next;
	40	u32 nistat;
	41
	42	INIT_LIST_HEAD(head);
	43
	44	for (pos=start; pos!=head; ) {
	45	cur = list_entry(pos, struct agp_3_5_dev, list);
	46	dev = cur->dev;
	47
	48	pci_read_config_dword(dev, cur->capndx+AGPNISTAT, &nistat);
	49	cur->maxbw = (nistat >> 16) & 0xff;
	50
	51	tmp = pos;
	52	pos = pos->next;
	53	agp_3_5_dev_list_insert(head, tmp);
	54	}
	55	}
	56
	57	/*
	58	* Initialize all isochronous transfer parameters for an AGP 3.0
	59	* node (i.e. a host bridge in combination with the adapters
	60	* lying behind it...)
	61	*/
	62
	63	static int agp_3_5_isochronous_node_enable(struct agp_bridge_data *bridge,
	64	struct agp_3_5_dev *dev_list, unsigned int ndevs)
	65	{
	66	/*
	67	* Convenience structure to make the calculations clearer
	68	* here. The field names come straight from the AGP 3.0 spec.
	69	*/
	70	struct isoch_data {
	71	u32 maxbw;
	72	u32 n;
	73	u32 y;
74	u32 l;
75	u32 rq;
76	struct agp_3_5_dev *dev;
77	};
78
79	struct pci_dev td = bridge->dev, dev;
80	struct list_head head = &dev_list->list, pos;
81	struct agp_3_5_dev *cur;
82	struct isoch_data *master, target;
83	unsigned int cdev = 0;
84	u32 mnistat, tnistat, tstatus, mcmd;
85	u16 tnicmd, mnicmd;
86	u8 mcapndx;
87	u32 tot_bw = 0, tot_n = 0, tot_rq = 0, y_max, rq_isoch, rq_async;
88	u32 step, rem, rem_isoch, rem_async;
89	int ret = 0;
90
91	/*
92	* We'll work with an array of isoch_data's (one for each
93	* device in dev_list) throughout this function.
94	*/
95	if ((master = kmalloc(ndevs * sizeof(*master), GFP_KERNEL)) == NULL) {
96	ret = -ENOMEM;
97	goto get_out;
98	}
99
100	/*
101	* Sort the device list by maxbw. We need to do this because the
102	* spec suggests that the devices with the smallest requirements
103	* have their resources allocated first, with all remaining resources
104	* falling to the device with the largest requirement.
105	*
106	* We don't exactly do this, we divide target resources by ndevs
107	* and split them amongst the AGP 3.0 devices. The remainder of such
108	* division operations are dropped on the last device, sort of like
109	* the spec mentions it should be done.
110	*
111	* We can't do this sort when we initially construct the dev_list
112	* because we don't know until this function whether isochronous
113	* transfers are enabled and consequently whether maxbw will mean
114	* anything.
115	*/
116	agp_3_5_dev_list_sort(dev_list, ndevs);
117
118	pci_read_config_dword(td, bridge->capndx+AGPNISTAT, &tnistat);
119	pci_read_config_dword(td, bridge->capndx+AGPSTAT, &tstatus);
120
121	/* Extract power-on defaults from the target */
122	target.maxbw = (tnistat >> 16) & 0xff;
123	target.n = (tnistat >> 8) & 0xff;
124	target.y = (tnistat >> 6) & 0x3;
125	target.l = (tnistat >> 3) & 0x7;
126	target.rq = (tstatus >> 24) & 0xff;
127
128	y_max = target.y;
129
130	/*
131	* Extract power-on defaults for each device in dev_list. Along
132	* the way, calculate the total isochronous bandwidth required
133	* by these devices and the largest requested payload size.
134	*/
135	list_for_each(pos, head) {
136	cur = list_entry(pos, struct agp_3_5_dev, list);
137	dev = cur->dev;
138
139	mcapndx = cur->capndx;
140
141	pci_read_config_dword(dev, cur->capndx+AGPNISTAT, &mnistat);
142
143	master[cdev].maxbw = (mnistat >> 16) & 0xff;
144	master[cdev].n = (mnistat >> 8) & 0xff;
145	master[cdev].y = (mnistat >> 6) & 0x3;
146	master[cdev].dev = cur;
147
148	tot_bw += master[cdev].maxbw;
149	y_max = max(y_max, master[cdev].y);
150
151	cdev++;
152	}
153
154	/* Check if this configuration has any chance of working */
155	if (tot_bw > target.maxbw) {
156	printk(KERN_ERR PFX "isochronous bandwidth required "
157	"by AGP 3.0 devices exceeds that which is supported by "
158	"the AGP 3.0 bridge!\n");
159	ret = -ENODEV;
160	goto free_and_exit;
161	}
162
163	target.y = y_max;
164
165	/*
166	* Write the calculated payload size into the target's NICMD
167	* register. Doing this directly effects the ISOCH_N value
168	* in the target's NISTAT register, so we need to do this now
169	* to get an accurate value for ISOCH_N later.
170	*/
171	pci_read_config_word(td, bridge->capndx+AGPNICMD, &tnicmd);
172	tnicmd &= ~(0x3 << 6);
173	tnicmd \|= target.y << 6;
174	pci_write_config_word(td, bridge->capndx+AGPNICMD, tnicmd);
175
176	/* Reread the target's ISOCH_N */
177	pci_read_config_dword(td, bridge->capndx+AGPNISTAT, &tnistat);
178	target.n = (tnistat >> 8) & 0xff;
179
180	/* Calculate the minimum ISOCH_N needed by each master */
181	for (cdev=0; cdev<ndevs; cdev++) {
182	master[cdev].y = target.y;
183	master[cdev].n = master[cdev].maxbw / (master[cdev].y + 1);
184
185	tot_n += master[cdev].n;
186	}
187
188	/* Exit if the minimal ISOCH_N allocation among the masters is more
189	* than the target can handle. */
190	if (tot_n > target.n) {
191	printk(KERN_ERR PFX "number of isochronous "
192	"transactions per period required by AGP 3.0 devices "
193	"exceeds that which is supported by the AGP 3.0 "
194	"bridge!\n");
195	ret = -ENODEV;
196	goto free_and_exit;
197	}
198
199	/* Calculate left over ISOCH_N capability in the target. We'll give
200	* this to the hungriest device (as per the spec) */
201	rem = target.n - tot_n;
202
203	/*
204	* Calculate the minimum isochronous RQ depth needed by each master.
205	* Along the way, distribute the extra ISOCH_N capability calculated
206	* above.
207	*/
208	for (cdev=0; cdev<ndevs; cdev++) {
209	/*
210	* This is a little subtle. If ISOCH_Y > 64B, then ISOCH_Y
211	* byte isochronous writes will be broken into 64B pieces.
212	* This means we need to budget more RQ depth to account for
213	* these kind of writes (each isochronous write is actually
214	* many writes on the AGP bus).
215	*/
216	master[cdev].rq = master[cdev].n;
217	if(master[cdev].y > 0x1)
218	master[cdev].rq *= (1 << (master[cdev].y - 1));
219
220	tot_rq += master[cdev].rq;
221
222	if (cdev == ndevs-1)
223	master[cdev].n += rem;
224	}
225
226	/* Figure the number of isochronous and asynchronous RQ slots the
227	* target is providing. */
228	rq_isoch = (target.y > 0x1) ? target.n * (1 << (target.y - 1)) : target.n;
229	rq_async = target.rq - rq_isoch;
230
231	/* Exit if the minimal RQ needs of the masters exceeds what the target
232	* can provide. */
233	if (tot_rq > rq_isoch) {
234	printk(KERN_ERR PFX "number of request queue slots "
235	"required by the isochronous bandwidth requested by "
236	"AGP 3.0 devices exceeds the number provided by the "
237	"AGP 3.0 bridge!\n");
238	ret = -ENODEV;
239	goto free_and_exit;
240	}
241
242	/* Calculate asynchronous RQ capability in the target (per master) as
243	* well as the total number of leftover isochronous RQ slots. */
244	step = rq_async / ndevs;
245	rem_async = step + (rq_async % ndevs);
246	rem_isoch = rq_isoch - tot_rq;
247
248	/* Distribute the extra RQ slots calculated above and write our
249	* isochronous settings out to the actual devices. */
250	for (cdev=0; cdev<ndevs; cdev++) {
251	cur = master[cdev].dev;
252	dev = cur->dev;
253
254	mcapndx = cur->capndx;
255
256	master[cdev].rq += (cdev == ndevs - 1)
257	? (rem_async + rem_isoch) : step;
258
259	pci_read_config_word(dev, cur->capndx+AGPNICMD, &mnicmd);
260	pci_read_config_dword(dev, cur->capndx+AGPCMD, &mcmd);
261
262	mnicmd &= ~(0xff << 8);
263	mnicmd &= ~(0x3 << 6);
264	mcmd &= ~(0xff << 24);
265
266	mnicmd \|= master[cdev].n << 8;
267	mnicmd \|= master[cdev].y << 6;
268	mcmd \|= master[cdev].rq << 24;
269
270	pci_write_config_dword(dev, cur->capndx+AGPCMD, mcmd);
271	pci_write_config_word(dev, cur->capndx+AGPNICMD, mnicmd);
272	}
273
274	free_and_exit:
275	kfree(master);
276
277	get_out:
278	return ret;
279	}
280
281	/*
282	* This function basically allocates request queue slots among the
283	* AGP 3.0 systems in nonisochronous nodes. The algorithm is
284	* pretty stupid, divide the total number of RQ slots provided by the
285	* target by ndevs. Distribute this many slots to each AGP 3.0 device,
286	* giving any left over slots to the last device in dev_list.
287	*/
288	static void agp_3_5_nonisochronous_node_enable(struct agp_bridge_data *bridge,
289	struct agp_3_5_dev *dev_list, unsigned int ndevs)
290	{
291	struct agp_3_5_dev *cur;
292	struct list_head head = &dev_list->list, pos;
293	u32 tstatus, mcmd;
294	u32 trq, mrq, rem;
295	unsigned int cdev = 0;
296
297	pci_read_config_dword(bridge->dev, bridge->capndx+AGPSTAT, &tstatus);
298
299	trq = (tstatus >> 24) & 0xff;
300	mrq = trq / ndevs;
301
302	rem = mrq + (trq % ndevs);
303
304	for (pos=head->next; cdev<ndevs; cdev++, pos=pos->next) {
305	cur = list_entry(pos, struct agp_3_5_dev, list);
306
307	pci_read_config_dword(cur->dev, cur->capndx+AGPCMD, &mcmd);
308	mcmd &= ~(0xff << 24);
309	mcmd \|= ((cdev == ndevs - 1) ? rem : mrq) << 24;
310	pci_write_config_dword(cur->dev, cur->capndx+AGPCMD, mcmd);
311	}
312	}
313
314	/*
315	* Fully configure and enable an AGP 3.0 host bridge and all the devices
316	* lying behind it.
317	*/
318	int agp_3_5_enable(struct agp_bridge_data *bridge)
319	{
320	struct pci_dev td = bridge->dev, dev = NULL;
321	u8 mcapndx;
322	u32 isoch, arqsz;
323	u32 tstatus, mstatus, ncapid;
324	u32 mmajor;
325	u16 mpstat;
326	struct agp_3_5_dev dev_list, cur;
327	struct list_head head, pos;
328	unsigned int ndevs = 0;
329	int ret = 0;
330
331	/* Extract some power-on defaults from the target */
332	pci_read_config_dword(td, bridge->capndx+AGPSTAT, &tstatus);
333	isoch = (tstatus >> 17) & 0x1;
334	if (isoch == 0) /* isoch xfers not available, bail out. */
335	return -ENODEV;
336
337	arqsz = (tstatus >> 13) & 0x7;
338
339	/*
340	* Allocate a head for our AGP 3.5 device list
341	* (multiple AGP v3 devices are allowed behind a single bridge).
342	*/
343	if ((dev_list = kmalloc(sizeof(*dev_list), GFP_KERNEL)) == NULL) {
344	ret = -ENOMEM;
345	goto get_out;
346	}
347	head = &dev_list->list;
348	INIT_LIST_HEAD(head);
349
350	/* Find all AGP devices, and add them to dev_list. */
351	for_each_pci_dev(dev) {
352	mcapndx = pci_find_capability(dev, PCI_CAP_ID_AGP);
353	if (mcapndx == 0)
354	continue;
355
356	switch ((dev->class >>8) & 0xff00) {
357	case 0x0600: /* Bridge */
358	/* Skip bridges. We should call this function for each one. */
359	continue;
360
361	case 0x0001: /* Unclassified device */
362	/* Don't know what this is, but log it for investigation. */
363	if (mcapndx != 0) {
364	printk (KERN_INFO PFX "Wacky, found unclassified AGP device. %x:%x\n",
365	dev->vendor, dev->device);
366	}
367	continue;
368
369	case 0x0300: /* Display controller */
370	case 0x0400: /* Multimedia controller */
371	if((cur = kmalloc(sizeof(*cur), GFP_KERNEL)) == NULL) {
372	ret = -ENOMEM;
373	goto free_and_exit;
374	}
375	cur->dev = dev;
376
377	pos = &cur->list;
378	list_add(pos, head);
379	ndevs++;
380	continue;
381
382	default:
383	continue;
384	}
385	}
386
387	/*
388	* Take an initial pass through the devices lying behind our host
389	* bridge. Make sure each one is actually an AGP 3.0 device, otherwise
390	* exit with an error message. Along the way store the AGP 3.0
391	* cap_ptr for each device
392	*/
393	list_for_each(pos, head) {
394	cur = list_entry(pos, struct agp_3_5_dev, list);
395	dev = cur->dev;
396
397	pci_read_config_word(dev, PCI_STATUS, &mpstat);
398	if ((mpstat & PCI_STATUS_CAP_LIST) == 0)
399	continue;
400
401	pci_read_config_byte(dev, PCI_CAPABILITY_LIST, &mcapndx);
402	if (mcapndx != 0) {
403	do {
404	pci_read_config_dword(dev, mcapndx, &ncapid);
405	if ((ncapid & 0xff) != 2)
406	mcapndx = (ncapid >> 8) & 0xff;
407	}
408	while (((ncapid & 0xff) != 2) && (mcapndx != 0));
409	}
410
411	if (mcapndx == 0) {
412	printk(KERN_ERR PFX "woah! Non-AGP device "
413	"found on the secondary bus of an AGP 3.5 bridge!\n");
414	ret = -ENODEV;
415	goto free_and_exit;
416	}
417
418	mmajor = (ncapid >> AGP_MAJOR_VERSION_SHIFT) & 0xf;
419	if (mmajor < 3) {
420	printk(KERN_ERR PFX "woah! AGP 2.0 device "
421	"found on the secondary bus of an AGP 3.5 "
422	"bridge operating with AGP 3.0 electricals!\n");
423	ret = -ENODEV;
424	goto free_and_exit;
425	}
426
427	cur->capndx = mcapndx;
428
429	pci_read_config_dword(dev, cur->capndx+AGPSTAT, &mstatus);
430
431	if (((mstatus >> 3) & 0x1) == 0) {
432	printk(KERN_ERR PFX "woah! AGP 3.x device "
433	"not operating in AGP 3.x mode found on the "
434	"secondary bus of an AGP 3.5 bridge operating "
435	"with AGP 3.0 electricals!\n");
436	ret = -ENODEV;
437	goto free_and_exit;
438	}
439	}
440
441	/*
442	* Call functions to divide target resources amongst the AGP 3.0
443	* masters. This process is dramatically different depending on
444	* whether isochronous transfers are supported.
445	*/
446	if (isoch) {
447	ret = agp_3_5_isochronous_node_enable(bridge, dev_list, ndevs);
448	if (ret) {
449	printk(KERN_INFO PFX "Something bad happened setting "
450	"up isochronous xfers. Falling back to "
451	"non-isochronous xfer mode.\n");
452	} else {
453	goto free_and_exit;
454	}
455	}
456	agp_3_5_nonisochronous_node_enable(bridge, dev_list, ndevs);
457
458	free_and_exit:
459	/* Be sure to free the dev_list */
460	for (pos=head->next; pos!=head; ) {
461	cur = list_entry(pos, struct agp_3_5_dev, list);
462
463	pos = pos->next;
464	kfree(cur);
465	}
466	kfree(dev_list);
467
468	get_out:
469	return ret;
470	}
471