diff options
Diffstat (limited to 'drivers/firewire/fw-iso.c')
| -rw-r--r-- | drivers/firewire/fw-iso.c | 176 |
1 files changed, 170 insertions, 6 deletions
diff --git a/drivers/firewire/fw-iso.c b/drivers/firewire/fw-iso.c index 39f3bacee40..a7b57b253b0 100644 --- a/drivers/firewire/fw-iso.c +++ b/drivers/firewire/fw-iso.c @@ -1,5 +1,7 @@ /* - * Isochronous IO functionality + * Isochronous I/O functionality: + * - Isochronous DMA context management + * - Isochronous bus resource management (channels, bandwidth), client side * * Copyright (C) 2006 Kristian Hoegsberg <krh@bitplanet.net> * @@ -18,15 +20,20 @@ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ -#include <linux/kernel.h> -#include <linux/module.h> #include <linux/dma-mapping.h> -#include <linux/vmalloc.h> +#include <linux/errno.h> +#include <linux/firewire-constants.h> +#include <linux/kernel.h> #include <linux/mm.h> +#include <linux/spinlock.h> +#include <linux/vmalloc.h> -#include "fw-transaction.h" #include "fw-topology.h" -#include "fw-device.h" +#include "fw-transaction.h" + +/* + * Isochronous DMA context management + */ int fw_iso_buffer_init(struct fw_iso_buffer *buffer, struct fw_card *card, int page_count, enum dma_data_direction direction) @@ -153,3 +160,160 @@ int fw_iso_context_stop(struct fw_iso_context *ctx) { return ctx->card->driver->stop_iso(ctx); } + +/* + * Isochronous bus resource management (channels, bandwidth), client side + */ + +static int manage_bandwidth(struct fw_card *card, int irm_id, int generation, + int bandwidth, bool allocate) +{ + __be32 data[2]; + int try, new, old = allocate ? BANDWIDTH_AVAILABLE_INITIAL : 0; + + /* + * On a 1394a IRM with low contention, try < 1 is enough. + * On a 1394-1995 IRM, we need at least try < 2. + * Let's just do try < 5. + */ + for (try = 0; try < 5; try++) { + new = allocate ? old - bandwidth : old + bandwidth; + if (new < 0 || new > BANDWIDTH_AVAILABLE_INITIAL) + break; + + data[0] = cpu_to_be32(old); + data[1] = cpu_to_be32(new); + switch (fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP, + irm_id, generation, SCODE_100, + CSR_REGISTER_BASE + CSR_BANDWIDTH_AVAILABLE, + data, sizeof(data))) { + case RCODE_GENERATION: + /* A generation change frees all bandwidth. */ + return allocate ? -EAGAIN : bandwidth; + + case RCODE_COMPLETE: + if (be32_to_cpup(data) == old) + return bandwidth; + + old = be32_to_cpup(data); + /* Fall through. */ + } + } + + return -EIO; +} + +static int manage_channel(struct fw_card *card, int irm_id, int generation, + __be32 channels_mask, u64 offset, bool allocate) +{ + __be32 data[2], c, old = allocate ? cpu_to_be32(~0) : 0; + int i, retry = 5; + + for (i = 0; i < 32; i++) { + c = cpu_to_be32(1 << (31 - i)); + if (!(channels_mask & c)) + continue; + + if (allocate == !(old & c)) + continue; + + data[0] = old; + data[1] = old ^ c; + switch (fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP, + irm_id, generation, SCODE_100, + offset, data, sizeof(data))) { + case RCODE_GENERATION: + /* A generation change frees all channels. */ + return allocate ? -EAGAIN : i; + + case RCODE_COMPLETE: + if (data[0] == old) + return i; + + old = data[0]; + + /* Is the IRM 1394a-2000 compliant? */ + if ((data[0] & c) != (data[1] & c)) + continue; + + /* 1394-1995 IRM, fall through to retry. */ + default: + if (retry--) + i--; + } + } + + return -EIO; +} + +static void deallocate_channel(struct fw_card *card, int irm_id, + int generation, int channel) +{ + __be32 mask; + u64 offset; + + mask = channel < 32 ? cpu_to_be32(1 << (31 - channel)) : + cpu_to_be32(1 << (63 - channel)); + offset = channel < 32 ? CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI : + CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO; + + manage_channel(card, irm_id, generation, mask, offset, false); +} + +/** + * fw_iso_resource_manage - Allocate or deallocate a channel and/or bandwidth + * + * In parameters: card, generation, channels_mask, bandwidth, allocate + * Out parameters: channel, bandwidth + * This function blocks (sleeps) during communication with the IRM. + * Allocates or deallocates at most one channel out of channels_mask. + * + * Returns channel < 0 if no channel was allocated or deallocated. + * Returns bandwidth = 0 if no bandwidth was allocated or deallocated. + * + * If generation is stale, deallocations succeed but allocations fail with + * channel = -EAGAIN. + * + * If channel (de)allocation fails, bandwidth (de)allocation fails too. + * If bandwidth allocation fails, no channel will be allocated either. + * If bandwidth deallocation fails, channel deallocation may still have been + * successful. + */ +void fw_iso_resource_manage(struct fw_card *card, int generation, + u64 channels_mask, int *channel, int *bandwidth, + bool allocate) +{ + __be32 channels_hi = cpu_to_be32(channels_mask >> 32); + __be32 channels_lo = cpu_to_be32(channels_mask); + int irm_id, ret, c = -EINVAL; + + spin_lock_irq(&card->lock); + irm_id = card->irm_node->node_id; + spin_unlock_irq(&card->lock); + + if (channels_hi) + c = manage_channel(card, irm_id, generation, channels_hi, + CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_HI, allocate); + if (channels_lo && c < 0) { + c = manage_channel(card, irm_id, generation, channels_lo, + CSR_REGISTER_BASE + CSR_CHANNELS_AVAILABLE_LO, allocate); + if (c >= 0) + c += 32; + } + *channel = c; + + if (channels_mask != 0 && c < 0) + *bandwidth = 0; + + if (*bandwidth == 0) + return; + + ret = manage_bandwidth(card, irm_id, generation, *bandwidth, allocate); + if (ret < 0) + *bandwidth = 0; + + if (ret < 0 && c >= 0 && allocate) { + deallocate_channel(card, irm_id, generation, c); + *channel = ret; + } +} |