diff options
Diffstat (limited to 'drivers/scsi/atari_scsi.c')
| -rw-r--r-- | drivers/scsi/atari_scsi.c | 144 |
1 files changed, 33 insertions, 111 deletions
diff --git a/drivers/scsi/atari_scsi.c b/drivers/scsi/atari_scsi.c index 78d1b2963f2c..a59ad94ea52b 100644 --- a/drivers/scsi/atari_scsi.c +++ b/drivers/scsi/atari_scsi.c @@ -14,55 +14,23 @@ * */ - -/**************************************************************************/ -/* */ -/* Notes for Falcon SCSI: */ -/* ---------------------- */ -/* */ -/* Since the Falcon SCSI uses the ST-DMA chip, that is shared among */ -/* several device drivers, locking and unlocking the access to this */ -/* chip is required. But locking is not possible from an interrupt, */ -/* since it puts the process to sleep if the lock is not available. */ -/* This prevents "late" locking of the DMA chip, i.e. locking it just */ -/* before using it, since in case of disconnection-reconnection */ -/* commands, the DMA is started from the reselection interrupt. */ -/* */ -/* Two possible schemes for ST-DMA-locking would be: */ -/* 1) The lock is taken for each command separately and disconnecting */ -/* is forbidden (i.e. can_queue = 1). */ -/* 2) The DMA chip is locked when the first command comes in and */ -/* released when the last command is finished and all queues are */ -/* empty. */ -/* The first alternative would result in bad performance, since the */ -/* interleaving of commands would not be used. The second is unfair to */ -/* other drivers using the ST-DMA, because the queues will seldom be */ -/* totally empty if there is a lot of disk traffic. */ -/* */ -/* For this reasons I decided to employ a more elaborate scheme: */ -/* - First, we give up the lock every time we can (for fairness), this */ -/* means every time a command finishes and there are no other commands */ -/* on the disconnected queue. */ -/* - If there are others waiting to lock the DMA chip, we stop */ -/* issuing commands, i.e. moving them onto the issue queue. */ -/* Because of that, the disconnected queue will run empty in a */ -/* while. Instead we go to sleep on a 'fairness_queue'. */ -/* - If the lock is released, all processes waiting on the fairness */ -/* queue will be woken. The first of them tries to re-lock the DMA, */ -/* the others wait for the first to finish this task. After that, */ -/* they can all run on and do their commands... */ -/* This sounds complicated (and it is it :-(), but it seems to be a */ -/* good compromise between fairness and performance: As long as no one */ -/* else wants to work with the ST-DMA chip, SCSI can go along as */ -/* usual. If now someone else comes, this behaviour is changed to a */ -/* "fairness mode": just already initiated commands are finished and */ -/* then the lock is released. The other one waiting will probably win */ -/* the race for locking the DMA, since it was waiting for longer. And */ -/* after it has finished, SCSI can go ahead again. Finally: I hope I */ -/* have not produced any deadlock possibilities! */ -/* */ -/**************************************************************************/ - +/* + * Notes for Falcon SCSI DMA + * + * The 5380 device is one of several that all share the DMA chip. Hence + * "locking" and "unlocking" access to this chip is required. + * + * Two possible schemes for ST DMA acquisition by atari_scsi are: + * 1) The lock is taken for each command separately (i.e. can_queue == 1). + * 2) The lock is taken when the first command arrives and released + * when the last command is finished (i.e. can_queue > 1). + * + * The first alternative limits SCSI bus utilization, since interleaving + * commands is not possible. The second gives better performance but is + * unfair to other drivers needing to use the ST DMA chip. In order to + * allow the IDE and floppy drivers equal access to the ST DMA chip + * the default is can_queue == 1. + */ #include <linux/module.h> #include <linux/types.h> @@ -83,13 +51,10 @@ #include <scsi/scsi_host.h> -/* Definitions for the core NCR5380 driver. */ - -#define REAL_DMA -#define SUPPORT_TAGS -#define MAX_TAGS 32 #define DMA_MIN_SIZE 32 +/* Definitions for the core NCR5380 driver. */ + #define NCR5380_implementation_fields /* none */ #define NCR5380_read(reg) atari_scsi_reg_read(reg) @@ -99,9 +64,9 @@ #define NCR5380_abort atari_scsi_abort #define NCR5380_info atari_scsi_info -#define NCR5380_dma_read_setup(instance, data, count) \ +#define NCR5380_dma_recv_setup(instance, data, count) \ atari_scsi_dma_setup(instance, data, count, 0) -#define NCR5380_dma_write_setup(instance, data, count) \ +#define NCR5380_dma_send_setup(instance, data, count) \ atari_scsi_dma_setup(instance, data, count, 1) #define NCR5380_dma_residual(instance) \ atari_scsi_dma_residual(instance) @@ -159,14 +124,11 @@ static inline unsigned long SCSI_DMA_GETADR(void) return adr; } -#ifdef REAL_DMA static void atari_scsi_fetch_restbytes(void); -#endif static unsigned char (*atari_scsi_reg_read)(unsigned char reg); static void (*atari_scsi_reg_write)(unsigned char reg, unsigned char value); -#ifdef REAL_DMA static unsigned long atari_dma_residual, atari_dma_startaddr; static short atari_dma_active; /* pointer to the dribble buffer */ @@ -185,7 +147,6 @@ static char *atari_dma_orig_addr; /* mask for address bits that can't be used with the ST-DMA */ static unsigned long atari_dma_stram_mask; #define STRAM_ADDR(a) (((a) & atari_dma_stram_mask) == 0) -#endif static int setup_can_queue = -1; module_param(setup_can_queue, int, 0); @@ -193,16 +154,12 @@ static int setup_cmd_per_lun = -1; module_param(setup_cmd_per_lun, int, 0); static int setup_sg_tablesize = -1; module_param(setup_sg_tablesize, int, 0); -static int setup_use_tagged_queuing = -1; -module_param(setup_use_tagged_queuing, int, 0); static int setup_hostid = -1; module_param(setup_hostid, int, 0); static int setup_toshiba_delay = -1; module_param(setup_toshiba_delay, int, 0); -#if defined(REAL_DMA) - static int scsi_dma_is_ignored_buserr(unsigned char dma_stat) { int i; @@ -255,12 +212,9 @@ static void scsi_dma_buserr(int irq, void *dummy) } #endif -#endif - static irqreturn_t scsi_tt_intr(int irq, void *dev) { -#ifdef REAL_DMA struct Scsi_Host *instance = dev; struct NCR5380_hostdata *hostdata = shost_priv(instance); int dma_stat; @@ -342,8 +296,6 @@ static irqreturn_t scsi_tt_intr(int irq, void *dev) tt_scsi_dma.dma_ctrl = 0; } -#endif /* REAL_DMA */ - NCR5380_intr(irq, dev); return IRQ_HANDLED; @@ -352,7 +304,6 @@ static irqreturn_t scsi_tt_intr(int irq, void *dev) static irqreturn_t scsi_falcon_intr(int irq, void *dev) { -#ifdef REAL_DMA struct Scsi_Host *instance = dev; struct NCR5380_hostdata *hostdata = shost_priv(instance); int dma_stat; @@ -405,15 +356,12 @@ static irqreturn_t scsi_falcon_intr(int irq, void *dev) atari_dma_orig_addr = NULL; } -#endif /* REAL_DMA */ - NCR5380_intr(irq, dev); return IRQ_HANDLED; } -#ifdef REAL_DMA static void atari_scsi_fetch_restbytes(void) { int nr; @@ -436,7 +384,6 @@ static void atari_scsi_fetch_restbytes(void) *dst++ = *src++; } } -#endif /* REAL_DMA */ /* This function releases the lock on the DMA chip if there is no @@ -464,6 +411,10 @@ static int falcon_get_lock(struct Scsi_Host *instance) if (IS_A_TT()) return 1; + if (stdma_is_locked_by(scsi_falcon_intr) && + instance->hostt->can_queue > 1) + return 1; + if (in_interrupt()) return stdma_try_lock(scsi_falcon_intr, instance); @@ -495,8 +446,7 @@ static int __init atari_scsi_setup(char *str) setup_sg_tablesize = ints[3]; if (ints[0] >= 4) setup_hostid = ints[4]; - if (ints[0] >= 5) - setup_use_tagged_queuing = ints[5]; + /* ints[5] (use_tagged_queuing) is ignored */ /* ints[6] (use_pdma) is ignored */ if (ints[0] >= 7) setup_toshiba_delay = ints[7]; @@ -508,8 +458,6 @@ __setup("atascsi=", atari_scsi_setup); #endif /* !MODULE */ -#if defined(REAL_DMA) - static unsigned long atari_scsi_dma_setup(struct Scsi_Host *instance, void *data, unsigned long count, int dir) @@ -545,9 +493,6 @@ static unsigned long atari_scsi_dma_setup(struct Scsi_Host *instance, */ dma_cache_maintenance(addr, count, dir); - if (count == 0) - printk(KERN_NOTICE "SCSI warning: DMA programmed for 0 bytes !\n"); - if (IS_A_TT()) { tt_scsi_dma.dma_ctrl = dir; SCSI_DMA_WRITE_P(dma_addr, addr); @@ -624,6 +569,9 @@ static unsigned long atari_dma_xfer_len(unsigned long wanted_len, { unsigned long possible_len, limit; + if (wanted_len < DMA_MIN_SIZE) + return 0; + if (IS_A_TT()) /* TT SCSI DMA can transfer arbitrary #bytes */ return wanted_len; @@ -703,9 +651,6 @@ static unsigned long atari_dma_xfer_len(unsigned long wanted_len, } -#endif /* REAL_DMA */ - - /* NCR5380 register access functions * * There are separate functions for TT and Falcon, because the access @@ -736,7 +681,7 @@ static void atari_scsi_falcon_reg_write(unsigned char reg, unsigned char value) } -#include "atari_NCR5380.c" +#include "NCR5380.c" static int atari_scsi_bus_reset(struct scsi_cmnd *cmd) { @@ -745,7 +690,6 @@ static int atari_scsi_bus_reset(struct scsi_cmnd *cmd) local_irq_save(flags); -#ifdef REAL_DMA /* Abort a maybe active DMA transfer */ if (IS_A_TT()) { tt_scsi_dma.dma_ctrl = 0; @@ -754,7 +698,6 @@ static int atari_scsi_bus_reset(struct scsi_cmnd *cmd) atari_dma_active = 0; atari_dma_orig_addr = NULL; } -#endif rv = NCR5380_bus_reset(cmd); @@ -781,6 +724,7 @@ static struct scsi_host_template atari_scsi_template = { .eh_abort_handler = atari_scsi_abort, .eh_bus_reset_handler = atari_scsi_bus_reset, .this_id = 7, + .cmd_per_lun = 2, .use_clustering = DISABLE_CLUSTERING, .cmd_size = NCR5380_CMD_SIZE, }; @@ -804,24 +748,11 @@ static int __init atari_scsi_probe(struct platform_device *pdev) atari_scsi_reg_write = atari_scsi_falcon_reg_write; } - /* The values for CMD_PER_LUN and CAN_QUEUE are somehow arbitrary. - * Higher values should work, too; try it! - * (But cmd_per_lun costs memory!) - * - * But there seems to be a bug somewhere that requires CAN_QUEUE to be - * 2*CMD_PER_LUN. At least on a TT, no spurious timeouts seen since - * changed CMD_PER_LUN... - * - * Note: The Falcon currently uses 8/1 setting due to unsolved problems - * with cmd_per_lun != 1 - */ if (ATARIHW_PRESENT(TT_SCSI)) { atari_scsi_template.can_queue = 16; - atari_scsi_template.cmd_per_lun = 8; atari_scsi_template.sg_tablesize = SG_ALL; } else { - atari_scsi_template.can_queue = 8; - atari_scsi_template.cmd_per_lun = 1; + atari_scsi_template.can_queue = 1; atari_scsi_template.sg_tablesize = SG_NONE; } @@ -850,8 +781,6 @@ static int __init atari_scsi_probe(struct platform_device *pdev) } } - -#ifdef REAL_DMA /* If running on a Falcon and if there's TT-Ram (i.e., more than one * memory block, since there's always ST-Ram in a Falcon), then * allocate a STRAM_BUFFER_SIZE byte dribble buffer for transfers @@ -867,7 +796,6 @@ static int __init atari_scsi_probe(struct platform_device *pdev) atari_dma_phys_buffer = atari_stram_to_phys(atari_dma_buffer); atari_dma_orig_addr = 0; } -#endif instance = scsi_host_alloc(&atari_scsi_template, sizeof(struct NCR5380_hostdata)); @@ -879,9 +807,6 @@ static int __init atari_scsi_probe(struct platform_device *pdev) instance->irq = irq->start; host_flags |= IS_A_TT() ? 0 : FLAG_LATE_DMA_SETUP; -#ifdef SUPPORT_TAGS - host_flags |= setup_use_tagged_queuing > 0 ? FLAG_TAGGED_QUEUING : 0; -#endif host_flags |= setup_toshiba_delay > 0 ? FLAG_TOSHIBA_DELAY : 0; error = NCR5380_init(instance, host_flags); @@ -897,7 +822,7 @@ static int __init atari_scsi_probe(struct platform_device *pdev) goto fail_irq; } tt_mfp.active_edge |= 0x80; /* SCSI int on L->H */ -#ifdef REAL_DMA + tt_scsi_dma.dma_ctrl = 0; atari_dma_residual = 0; @@ -919,17 +844,14 @@ static int __init atari_scsi_probe(struct platform_device *pdev) hostdata->read_overruns = 4; } -#endif } else { /* Nothing to do for the interrupt: the ST-DMA is initialized * already. */ -#ifdef REAL_DMA atari_dma_residual = 0; atari_dma_active = 0; atari_dma_stram_mask = (ATARIHW_PRESENT(EXTD_DMA) ? 0x00000000 : 0xff000000); -#endif } NCR5380_maybe_reset_bus(instance); |