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spibus: extend API: add cs_delay ivar, KEEP_CS and NO_SLEEP flags

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These feature are required for an upcoming Apple MacBook topcase
(HID over SPI) driver:

A delay after toggling CS is required to avoid anomalies like an extra
junk byte in front of the message. Keeping CS asserted is required to
be able to read a status report after writing a command. (The device
won't return the status if CS was deasserted.)

Sleep is not allowed in the interrupt context where the Apple input
driver runs its transactions. Use a flag to tell the SPI driver to
avoid mtx_sleep.

Reviewed by:	manu (ok to SPI part of larger patch)
MFC afret:	1 month
Differential revision:	https://reviews.freebsd.org/D29534
This commit is contained in:
Val Packett 2023-04-24 12:41:52 +03:00 committed by Vladimir Kondratyev
parent b344bd3a7d
commit 3c08673438
3 changed files with 13 additions and 0 deletions
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4
sys/dev/spibus/spi.h
View File

@ -34,9 +34,13 @@ struct spi_command {
uint32_t tx_data_sz;
void *rx_data;
uint32_t rx_data_sz;
uint32_t flags;
};
#define SPI_COMMAND_INITIALIZER { 0 }
#define SPI_FLAG_KEEP_CS 0x1 /* Keep chip select asserted */
#define SPI_FLAG_NO_SLEEP 0x2 /* Prevent driver from sleeping (use polling) */
#define SPI_CHIP_SELECT_HIGH 0x1 /* Chip select high (else low) */
#ifdef FDT

6
sys/dev/spibus/spibus.c
View File

@ -146,6 +146,9 @@ spibus_read_ivar(device_t bus, device_t child, int which, uintptr_t *result)
case SPIBUS_IVAR_CLOCK:
*(uint32_t *)result = devi->clock;
break;
case SPIBUS_IVAR_CS_DELAY:
*(uint32_t *)result = devi->cs_delay;
break;
}
return (0);
}
@ -174,6 +177,9 @@ spibus_write_ivar(device_t bus, device_t child, int which, uintptr_t value)
return (EINVAL);
devi->mode = (uint32_t)value;
break;
case SPIBUS_IVAR_CS_DELAY:
devi->cs_delay = (uint32_t)value;
break;
default:
return (EINVAL);
}

3
sys/dev/spibus/spibusvar.h
View File

@ -43,6 +43,7 @@ struct spibus_ivar
uint32_t cs;
uint32_t mode;
uint32_t clock;
uint32_t cs_delay;
struct resource_list rl;
};
@ -52,6 +53,7 @@ enum {
SPIBUS_IVAR_CS, /* chip select that we're on */
SPIBUS_IVAR_MODE, /* SPI mode (0-3) */
SPIBUS_IVAR_CLOCK, /* maximum clock freq for device */
SPIBUS_IVAR_CS_DELAY, /* delay in microseconds after toggling chip select */
};
#define SPIBUS_ACCESSOR(A, B, T) \
@ -71,6 +73,7 @@ spibus_set_ ## A(device_t dev, T t) \
SPIBUS_ACCESSOR(cs, CS, uint32_t)
SPIBUS_ACCESSOR(mode, MODE, uint32_t)
SPIBUS_ACCESSOR(clock, CLOCK, uint32_t)
SPIBUS_ACCESSOR(cs_delay, CS_DELAY, uint32_t)
extern driver_t spibus_driver;
extern driver_t ofw_spibus_driver;