diff options
Diffstat (limited to 'drivers/scsi/scsi_dma.c')
| -rw-r--r-- | drivers/scsi/scsi_dma.c | 449 |
1 files changed, 449 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_dma.c b/drivers/scsi/scsi_dma.c new file mode 100644 index 000000000..c0eb4baa0 --- /dev/null +++ b/drivers/scsi/scsi_dma.c @@ -0,0 +1,449 @@ +/* + * scsi_dma.c Copyright (C) 2000 Eric Youngdale + * + * mid-level SCSI DMA bounce buffer allocator + * + */ + +#define __NO_VERSION__ +#include <linux/config.h> +#include <linux/module.h> +#include <linux/blk.h> + + +#include "scsi.h" +#include "hosts.h" +#include "constants.h" + +#ifdef CONFIG_KMOD +#include <linux/kmod.h> +#endif + +/* + * PAGE_SIZE must be a multiple of the sector size (512). True + * for all reasonably recent architectures (even the VAX...). + */ +#define SECTOR_SIZE 512 +#define SECTORS_PER_PAGE (PAGE_SIZE/SECTOR_SIZE) + +#if SECTORS_PER_PAGE <= 8 +typedef unsigned char FreeSectorBitmap; +#elif SECTORS_PER_PAGE <= 32 +typedef unsigned int FreeSectorBitmap; +#else +#error You lose. +#endif + +/* + * Used for access to internal allocator used for DMA safe buffers. + */ +static spinlock_t allocator_request_lock = SPIN_LOCK_UNLOCKED; + +static FreeSectorBitmap *dma_malloc_freelist = NULL; +static int need_isa_bounce_buffers; +static unsigned int dma_sectors = 0; +unsigned int scsi_dma_free_sectors = 0; +unsigned int scsi_need_isa_buffer = 0; +static unsigned char **dma_malloc_pages = NULL; + +/* + * Function: scsi_malloc + * + * Purpose: Allocate memory from the DMA-safe pool. + * + * Arguments: len - amount of memory we need. + * + * Lock status: No locks assumed to be held. This function is SMP-safe. + * + * Returns: Pointer to memory block. + * + * Notes: Prior to the new queue code, this function was not SMP-safe. + * This function can only allocate in units of sectors + * (i.e. 512 bytes). + * + * We cannot use the normal system allocator becuase we need + * to be able to guarantee that we can process a complete disk + * I/O request without touching the system allocator. Think + * about it - if the system were heavily swapping, and tried to + * write out a block of memory to disk, and the SCSI code needed + * to allocate more memory in order to be able to write the + * data to disk, you would wedge the system. + */ +void *scsi_malloc(unsigned int len) +{ + unsigned int nbits, mask; + unsigned long flags; + + int i, j; + if (len % SECTOR_SIZE != 0 || len > PAGE_SIZE) + return NULL; + + nbits = len >> 9; + mask = (1 << nbits) - 1; + + spin_lock_irqsave(&allocator_request_lock, flags); + + for (i = 0; i < dma_sectors / SECTORS_PER_PAGE; i++) + for (j = 0; j <= SECTORS_PER_PAGE - nbits; j++) { + if ((dma_malloc_freelist[i] & (mask << j)) == 0) { + dma_malloc_freelist[i] |= (mask << j); + scsi_dma_free_sectors -= nbits; +#ifdef DEBUG + SCSI_LOG_MLQUEUE(3, printk("SMalloc: %d %p [From:%p]\n", len, dma_malloc_pages[i] + (j << 9))); + printk("SMalloc: %d %p [From:%p]\n", len, dma_malloc_pages[i] + (j << 9)); +#endif + spin_unlock_irqrestore(&allocator_request_lock, flags); + return (void *) ((unsigned long) dma_malloc_pages[i] + (j << 9)); + } + } + spin_unlock_irqrestore(&allocator_request_lock, flags); + return NULL; /* Nope. No more */ +} + +/* + * Function: scsi_free + * + * Purpose: Free memory into the DMA-safe pool. + * + * Arguments: ptr - data block we are freeing. + * len - size of block we are freeing. + * + * Lock status: No locks assumed to be held. This function is SMP-safe. + * + * Returns: Nothing + * + * Notes: This function *must* only be used to free memory + * allocated from scsi_malloc(). + * + * Prior to the new queue code, this function was not SMP-safe. + * This function can only allocate in units of sectors + * (i.e. 512 bytes). + */ +int scsi_free(void *obj, unsigned int len) +{ + unsigned int page, sector, nbits, mask; + unsigned long flags; + +#ifdef DEBUG + unsigned long ret = 0; + +#ifdef __mips__ + __asm__ __volatile__("move\t%0,$31":"=r"(ret)); +#else + ret = __builtin_return_address(0); +#endif + printk("scsi_free %p %d\n", obj, len); + SCSI_LOG_MLQUEUE(3, printk("SFree: %p %d\n", obj, len)); +#endif + + spin_lock_irqsave(&allocator_request_lock, flags); + + for (page = 0; page < dma_sectors / SECTORS_PER_PAGE; page++) { + unsigned long page_addr = (unsigned long) dma_malloc_pages[page]; + if ((unsigned long) obj >= page_addr && + (unsigned long) obj < page_addr + PAGE_SIZE) { + sector = (((unsigned long) obj) - page_addr) >> 9; + + nbits = len >> 9; + mask = (1 << nbits) - 1; + + if ((mask << sector) >= (1 << SECTORS_PER_PAGE)) + panic("scsi_free:Bad memory alignment"); + + if ((dma_malloc_freelist[page] & + (mask << sector)) != (mask << sector)) { +#ifdef DEBUG + printk("scsi_free(obj=%p, len=%d) called from %08lx\n", + obj, len, ret); +#endif + panic("scsi_free:Trying to free unused memory"); + } + scsi_dma_free_sectors += nbits; + dma_malloc_freelist[page] &= ~(mask << sector); + spin_unlock_irqrestore(&allocator_request_lock, flags); + return 0; + } + } + panic("scsi_free:Bad offset"); +} + + +/* + * Function: scsi_resize_dma_pool + * + * Purpose: Ensure that the DMA pool is sufficiently large to be + * able to guarantee that we can always process I/O requests + * without calling the system allocator. + * + * Arguments: None. + * + * Lock status: No locks assumed to be held. This function is SMP-safe. + * + * Returns: Nothing + * + * Notes: Prior to the new queue code, this function was not SMP-safe. + * Go through the device list and recompute the most appropriate + * size for the dma pool. Then grab more memory (as required). + */ +void scsi_resize_dma_pool(void) +{ + int i, k; + unsigned long size; + unsigned long flags; + struct Scsi_Host *shpnt; + struct Scsi_Host *host = NULL; + Scsi_Device *SDpnt; + FreeSectorBitmap *new_dma_malloc_freelist = NULL; + unsigned int new_dma_sectors = 0; + unsigned int new_need_isa_buffer = 0; + unsigned char **new_dma_malloc_pages = NULL; + int out_of_space = 0; + + spin_lock_irqsave(&allocator_request_lock, flags); + + if (!scsi_hostlist) { + /* + * Free up the DMA pool. + */ + if (scsi_dma_free_sectors != dma_sectors) + panic("SCSI DMA pool memory leak %d %d\n", scsi_dma_free_sectors, dma_sectors); + + for (i = 0; i < dma_sectors / SECTORS_PER_PAGE; i++) + free_pages((unsigned long) dma_malloc_pages[i], 0); + if (dma_malloc_pages) + kfree((char *) dma_malloc_pages); + dma_malloc_pages = NULL; + if (dma_malloc_freelist) + kfree((char *) dma_malloc_freelist); + dma_malloc_freelist = NULL; + dma_sectors = 0; + scsi_dma_free_sectors = 0; + spin_unlock_irqrestore(&allocator_request_lock, flags); + return; + } + /* Next, check to see if we need to extend the DMA buffer pool */ + + new_dma_sectors = 2 * SECTORS_PER_PAGE; /* Base value we use */ + + if (__pa(high_memory) - 1 > ISA_DMA_THRESHOLD) + need_isa_bounce_buffers = 1; + else + need_isa_bounce_buffers = 0; + + if (scsi_devicelist) + for (shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next) + new_dma_sectors += SECTORS_PER_PAGE; /* Increment for each host */ + + for (host = scsi_hostlist; host; host = host->next) { + for (SDpnt = host->host_queue; SDpnt; SDpnt = SDpnt->next) { + /* + * sd and sr drivers allocate scatterlists. + * sr drivers may allocate for each command 1x2048 or 2x1024 extra + * buffers for 2k sector size and 1k fs. + * sg driver allocates buffers < 4k. + * st driver does not need buffers from the dma pool. + * estimate 4k buffer/command for devices of unknown type (should panic). + */ + if (SDpnt->type == TYPE_WORM || SDpnt->type == TYPE_ROM || + SDpnt->type == TYPE_DISK || SDpnt->type == TYPE_MOD) { + int nents = host->sg_tablesize; +#ifdef DMA_CHUNK_SIZE + /* If the architecture does DMA sg merging, make sure + we count with at least 64 entries even for HBAs + which handle very few sg entries. */ + if (nents < 64) nents = 64; +#endif + new_dma_sectors += ((nents * + sizeof(struct scatterlist) + 511) >> 9) * + SDpnt->queue_depth; + if (SDpnt->type == TYPE_WORM || SDpnt->type == TYPE_ROM) + new_dma_sectors += (2048 >> 9) * SDpnt->queue_depth; + } else if (SDpnt->type == TYPE_SCANNER || + SDpnt->type == TYPE_PROCESSOR || + SDpnt->type == TYPE_MEDIUM_CHANGER || + SDpnt->type == TYPE_ENCLOSURE) { + new_dma_sectors += (4096 >> 9) * SDpnt->queue_depth; + } else { + if (SDpnt->type != TYPE_TAPE) { + printk("resize_dma_pool: unknown device type %d\n", SDpnt->type); + new_dma_sectors += (4096 >> 9) * SDpnt->queue_depth; + } + } + + if (host->unchecked_isa_dma && + need_isa_bounce_buffers && + SDpnt->type != TYPE_TAPE) { + new_dma_sectors += (PAGE_SIZE >> 9) * host->sg_tablesize * + SDpnt->queue_depth; + new_need_isa_buffer++; + } + } + } + +#ifdef DEBUG_INIT + printk("resize_dma_pool: needed dma sectors = %d\n", new_dma_sectors); +#endif + + /* limit DMA memory to 32MB: */ + new_dma_sectors = (new_dma_sectors + 15) & 0xfff0; + + /* + * We never shrink the buffers - this leads to + * race conditions that I would rather not even think + * about right now. + */ +#if 0 /* Why do this? No gain and risks out_of_space */ + if (new_dma_sectors < dma_sectors) + new_dma_sectors = dma_sectors; +#endif + if (new_dma_sectors <= dma_sectors) { + spin_unlock_irqrestore(&allocator_request_lock, flags); + return; /* best to quit while we are in front */ + } + + for (k = 0; k < 20; ++k) { /* just in case */ + out_of_space = 0; + size = (new_dma_sectors / SECTORS_PER_PAGE) * + sizeof(FreeSectorBitmap); + new_dma_malloc_freelist = (FreeSectorBitmap *) + kmalloc(size, GFP_ATOMIC); + if (new_dma_malloc_freelist) { + memset(new_dma_malloc_freelist, 0, size); + size = (new_dma_sectors / SECTORS_PER_PAGE) * + sizeof(*new_dma_malloc_pages); + new_dma_malloc_pages = (unsigned char **) + kmalloc(size, GFP_ATOMIC); + if (!new_dma_malloc_pages) { + size = (new_dma_sectors / SECTORS_PER_PAGE) * + sizeof(FreeSectorBitmap); + kfree((char *) new_dma_malloc_freelist); + out_of_space = 1; + } else { + memset(new_dma_malloc_pages, 0, size); + } + } else + out_of_space = 1; + + if ((!out_of_space) && (new_dma_sectors > dma_sectors)) { + for (i = dma_sectors / SECTORS_PER_PAGE; + i < new_dma_sectors / SECTORS_PER_PAGE; i++) { + new_dma_malloc_pages[i] = (unsigned char *) + __get_free_pages(GFP_ATOMIC | GFP_DMA, 0); + if (!new_dma_malloc_pages[i]) + break; + } + if (i != new_dma_sectors / SECTORS_PER_PAGE) { /* clean up */ + int k = i; + + out_of_space = 1; + for (i = 0; i < k; ++i) + free_pages((unsigned long) new_dma_malloc_pages[i], 0); + } + } + if (out_of_space) { /* try scaling down new_dma_sectors request */ + printk("scsi::resize_dma_pool: WARNING, dma_sectors=%u, " + "wanted=%u, scaling\n", dma_sectors, new_dma_sectors); + if (new_dma_sectors < (8 * SECTORS_PER_PAGE)) + break; /* pretty well hopeless ... */ + new_dma_sectors = (new_dma_sectors * 3) / 4; + new_dma_sectors = (new_dma_sectors + 15) & 0xfff0; + if (new_dma_sectors <= dma_sectors) + break; /* stick with what we have got */ + } else + break; /* found space ... */ + } /* end of for loop */ + if (out_of_space) { + spin_unlock_irqrestore(&allocator_request_lock, flags); + scsi_need_isa_buffer = new_need_isa_buffer; /* some useful info */ + printk(" WARNING, not enough memory, pool not expanded\n"); + return; + } + /* When we dick with the actual DMA list, we need to + * protect things + */ + if (dma_malloc_freelist) { + size = (dma_sectors / SECTORS_PER_PAGE) * sizeof(FreeSectorBitmap); + memcpy(new_dma_malloc_freelist, dma_malloc_freelist, size); + kfree((char *) dma_malloc_freelist); + } + dma_malloc_freelist = new_dma_malloc_freelist; + + if (dma_malloc_pages) { + size = (dma_sectors / SECTORS_PER_PAGE) * sizeof(*dma_malloc_pages); + memcpy(new_dma_malloc_pages, dma_malloc_pages, size); + kfree((char *) dma_malloc_pages); + } + scsi_dma_free_sectors += new_dma_sectors - dma_sectors; + dma_malloc_pages = new_dma_malloc_pages; + dma_sectors = new_dma_sectors; + scsi_need_isa_buffer = new_need_isa_buffer; + + spin_unlock_irqrestore(&allocator_request_lock, flags); + +#ifdef DEBUG_INIT + printk("resize_dma_pool: dma free sectors = %d\n", scsi_dma_free_sectors); + printk("resize_dma_pool: dma sectors = %d\n", dma_sectors); + printk("resize_dma_pool: need isa buffers = %d\n", scsi_need_isa_buffer); +#endif +} + +/* + * Function: scsi_init_minimal_dma_pool + * + * Purpose: Allocate a minimal (1-page) DMA pool. + * + * Arguments: None. + * + * Lock status: No locks assumed to be held. This function is SMP-safe. + * + * Returns: Nothing + * + * Notes: + */ +int scsi_init_minimal_dma_pool(void) +{ + unsigned long size; + unsigned long flags; + int has_space = 0; + + spin_lock_irqsave(&allocator_request_lock, flags); + + dma_sectors = PAGE_SIZE / SECTOR_SIZE; + scsi_dma_free_sectors = dma_sectors; + /* + * Set up a minimal DMA buffer list - this will be used during scan_scsis + * in some cases. + */ + + /* One bit per sector to indicate free/busy */ + size = (dma_sectors / SECTORS_PER_PAGE) * sizeof(FreeSectorBitmap); + dma_malloc_freelist = (FreeSectorBitmap *) + kmalloc(size, GFP_ATOMIC); + if (dma_malloc_freelist) { + memset(dma_malloc_freelist, 0, size); + /* One pointer per page for the page list */ + dma_malloc_pages = (unsigned char **) kmalloc( + (dma_sectors / SECTORS_PER_PAGE) * sizeof(*dma_malloc_pages), + GFP_ATOMIC); + if (dma_malloc_pages) { + memset(dma_malloc_pages, 0, size); + dma_malloc_pages[0] = (unsigned char *) + __get_free_pages(GFP_ATOMIC | GFP_DMA, 0); + if (dma_malloc_pages[0]) + has_space = 1; + } + } + if (!has_space) { + if (dma_malloc_freelist) { + kfree((char *) dma_malloc_freelist); + if (dma_malloc_pages) + kfree((char *) dma_malloc_pages); + } + spin_unlock_irqrestore(&allocator_request_lock, flags); + printk("scsi::init_module: failed, out of memory\n"); + return 1; + } + + spin_unlock_irqrestore(&allocator_request_lock, flags); + return 0; +} |