From c15f6ed3a18f10cdc33f64906ab353f17a6df114 Mon Sep 17 00:00:00 2001 From: Nicolas Boichat Date: Mon, 17 Aug 2015 11:52:54 +0800 Subject: spi: bitbang: Replace spinlock by mutex chipselect (in the case of spi-gpio: spi_gpio_chipselect, which calls gpiod_set_raw_value_cansleep) can sleep, so we should not hold a spinlock while calling it from spi_bitbang_setup. This issue was introduced by this commit, which converted spi-gpio to cansleep variants: d9dda5a191 "spi: spi-gpio: Use 'cansleep' variants to access GPIO" Replacing the lock variable by a mutex fixes the issue: This is safe as all instances where the lock is used are called from contexts that can sleep. Finally, update spi-ppc4xx and and spi-s3c24xx to use mutex functions, as they directly hold the lock for similar purpose. Signed-off-by: Nicolas Boichat Signed-off-by: Mark Brown --- drivers/spi/spi-bitbang.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) (limited to 'drivers/spi/spi-bitbang.c') diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c index 840a4984d365..ef43ef507c9a 100644 --- a/drivers/spi/spi-bitbang.c +++ b/drivers/spi/spi-bitbang.c @@ -180,7 +180,6 @@ int spi_bitbang_setup(struct spi_device *spi) { struct spi_bitbang_cs *cs = spi->controller_state; struct spi_bitbang *bitbang; - unsigned long flags; bitbang = spi_master_get_devdata(spi->master); @@ -210,12 +209,12 @@ int spi_bitbang_setup(struct spi_device *spi) */ /* deselect chip (low or high) */ - spin_lock_irqsave(&bitbang->lock, flags); + mutex_lock(&bitbang->lock); if (!bitbang->busy) { bitbang->chipselect(spi, BITBANG_CS_INACTIVE); ndelay(cs->nsecs); } - spin_unlock_irqrestore(&bitbang->lock, flags); + mutex_unlock(&bitbang->lock); return 0; } @@ -255,13 +254,12 @@ static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t) static int spi_bitbang_prepare_hardware(struct spi_master *spi) { struct spi_bitbang *bitbang; - unsigned long flags; bitbang = spi_master_get_devdata(spi); - spin_lock_irqsave(&bitbang->lock, flags); + mutex_lock(&bitbang->lock); bitbang->busy = 1; - spin_unlock_irqrestore(&bitbang->lock, flags); + mutex_unlock(&bitbang->lock); return 0; } @@ -378,13 +376,12 @@ static int spi_bitbang_transfer_one(struct spi_master *master, static int spi_bitbang_unprepare_hardware(struct spi_master *spi) { struct spi_bitbang *bitbang; - unsigned long flags; bitbang = spi_master_get_devdata(spi); - spin_lock_irqsave(&bitbang->lock, flags); + mutex_lock(&bitbang->lock); bitbang->busy = 0; - spin_unlock_irqrestore(&bitbang->lock, flags); + mutex_unlock(&bitbang->lock); return 0; } @@ -427,7 +424,7 @@ int spi_bitbang_start(struct spi_bitbang *bitbang) if (!master || !bitbang->chipselect) return -EINVAL; - spin_lock_init(&bitbang->lock); + mutex_init(&bitbang->lock); if (!master->mode_bits) master->mode_bits = SPI_CPOL | SPI_CPHA | bitbang->flags; -- cgit v1.2.3 From e30d8f23926b70a003d9fb16b49bfe23f01269da Mon Sep 17 00:00:00 2001 From: Heiner Kallweit Date: Tue, 29 Sep 2015 23:09:33 +0200 Subject: spi: bitbang: remove unneeded check Remove an unneeded check. The SPI core (__spi_validate) takes care that these fields are always populated. Signed-off-by: Heiner Kallweit Signed-off-by: Mark Brown --- drivers/spi/spi-bitbang.c | 18 ++++-------------- 1 file changed, 4 insertions(+), 14 deletions(-) (limited to 'drivers/spi/spi-bitbang.c') diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c index ef43ef507c9a..ad3168dc45e7 100644 --- a/drivers/spi/spi-bitbang.c +++ b/drivers/spi/spi-bitbang.c @@ -272,7 +272,6 @@ static int spi_bitbang_transfer_one(struct spi_master *master, struct spi_transfer *t = NULL; unsigned cs_change; int status; - int do_setup = -1; struct spi_device *spi = m->spi; bitbang = spi_master_get_devdata(master); @@ -288,19 +287,10 @@ static int spi_bitbang_transfer_one(struct spi_master *master, list_for_each_entry(t, &m->transfers, transfer_list) { - /* override speed or wordsize? */ - if (t->speed_hz || t->bits_per_word) - do_setup = 1; - - /* init (-1) or override (1) transfer params */ - if (do_setup != 0) { - if (bitbang->setup_transfer) { - status = bitbang->setup_transfer(spi, t); - if (status < 0) - break; - } - if (do_setup == -1) - do_setup = 0; + if (bitbang->setup_transfer) { + status = bitbang->setup_transfer(spi, t); + if (status < 0) + break; } /* set up default clock polarity, and activate chip; -- cgit v1.2.3 From 0037686596832572bbca05ab168d9884d7d704c1 Mon Sep 17 00:00:00 2001 From: Heiner Kallweit Date: Tue, 29 Sep 2015 23:15:53 +0200 Subject: spi: bitbang: switch to the generic implementation of transfer_one_message Change the bitbang driver to use the generic implementation of transfer_one_message. This simplifies the bitbang driver code and provides benefits like the statistics in the generic implementation. Successfully tested on a IMX6-based system (spi-imx) and on a MIPS-based router (OpenWRT with spi-ath79). Signed-off-by: Heiner Kallweit Signed-off-by: Mark Brown --- drivers/spi/spi-bitbang.c | 125 +++++++++++++--------------------------------- 1 file changed, 36 insertions(+), 89 deletions(-) (limited to 'drivers/spi/spi-bitbang.c') diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c index ad3168dc45e7..3aa9e6e3dac8 100644 --- a/drivers/spi/spi-bitbang.c +++ b/drivers/spi/spi-bitbang.c @@ -24,6 +24,8 @@ #include #include +#define SPI_BITBANG_CS_DELAY 100 + /*----------------------------------------------------------------------*/ @@ -265,100 +267,28 @@ static int spi_bitbang_prepare_hardware(struct spi_master *spi) } static int spi_bitbang_transfer_one(struct spi_master *master, - struct spi_message *m) + struct spi_device *spi, + struct spi_transfer *transfer) { - struct spi_bitbang *bitbang; - unsigned nsecs; - struct spi_transfer *t = NULL; - unsigned cs_change; - int status; - struct spi_device *spi = m->spi; - - bitbang = spi_master_get_devdata(master); - - /* FIXME this is made-up ... the correct value is known to - * word-at-a-time bitbang code, and presumably chipselect() - * should enforce these requirements too? - */ - nsecs = 100; - - cs_change = 1; - status = 0; - - list_for_each_entry(t, &m->transfers, transfer_list) { - - if (bitbang->setup_transfer) { - status = bitbang->setup_transfer(spi, t); - if (status < 0) - break; - } - - /* set up default clock polarity, and activate chip; - * this implicitly updates clock and spi modes as - * previously recorded for this device via setup(). - * (and also deselects any other chip that might be - * selected ...) - */ - if (cs_change) { - bitbang->chipselect(spi, BITBANG_CS_ACTIVE); - ndelay(nsecs); - } - cs_change = t->cs_change; - if (!t->tx_buf && !t->rx_buf && t->len) { - status = -EINVAL; - break; - } - - /* transfer data. the lower level code handles any - * new dma mappings it needs. our caller always gave - * us dma-safe buffers. - */ - if (t->len) { - /* REVISIT dma API still needs a designated - * DMA_ADDR_INVALID; ~0 might be better. - */ - if (!m->is_dma_mapped) - t->rx_dma = t->tx_dma = 0; - status = bitbang->txrx_bufs(spi, t); - } - if (status > 0) - m->actual_length += status; - if (status != t->len) { - /* always report some kind of error */ - if (status >= 0) - status = -EREMOTEIO; - break; - } - status = 0; + struct spi_bitbang *bitbang = spi_master_get_devdata(master); + int status = 0; - /* protocol tweaks before next transfer */ - if (t->delay_usecs) - udelay(t->delay_usecs); - - if (cs_change && - !list_is_last(&t->transfer_list, &m->transfers)) { - /* sometimes a short mid-message deselect of the chip - * may be needed to terminate a mode or command - */ - ndelay(nsecs); - bitbang->chipselect(spi, BITBANG_CS_INACTIVE); - ndelay(nsecs); - } + if (bitbang->setup_transfer) { + status = bitbang->setup_transfer(spi, transfer); + if (status < 0) + goto out; } - m->status = status; + if (transfer->len) + status = bitbang->txrx_bufs(spi, transfer); - /* normally deactivate chipselect ... unless no error and - * cs_change has hinted that the next message will probably - * be for this chip too. - */ - if (!(status == 0 && cs_change)) { - ndelay(nsecs); - bitbang->chipselect(spi, BITBANG_CS_INACTIVE); - ndelay(nsecs); - } + if (status == transfer->len) + status = 0; + else if (status >= 0) + status = -EREMOTEIO; - spi_finalize_current_message(master); +out: + spi_finalize_current_transfer(master); return status; } @@ -376,6 +306,22 @@ static int spi_bitbang_unprepare_hardware(struct spi_master *spi) return 0; } +static void spi_bitbang_set_cs(struct spi_device *spi, bool enable) +{ + struct spi_bitbang *bitbang = spi_master_get_devdata(spi->master); + + /* SPI core provides CS high / low, but bitbang driver + * expects CS active + * spi device driver takes care of handling SPI_CS_HIGH + */ + enable = (!!(spi->mode & SPI_CS_HIGH) == enable); + + ndelay(SPI_BITBANG_CS_DELAY); + bitbang->chipselect(spi, enable ? BITBANG_CS_ACTIVE : + BITBANG_CS_INACTIVE); + ndelay(SPI_BITBANG_CS_DELAY); +} + /*----------------------------------------------------------------------*/ /** @@ -424,7 +370,8 @@ int spi_bitbang_start(struct spi_bitbang *bitbang) master->prepare_transfer_hardware = spi_bitbang_prepare_hardware; master->unprepare_transfer_hardware = spi_bitbang_unprepare_hardware; - master->transfer_one_message = spi_bitbang_transfer_one; + master->transfer_one = spi_bitbang_transfer_one; + master->set_cs = spi_bitbang_set_cs; if (!bitbang->txrx_bufs) { bitbang->use_dma = 0; -- cgit v1.2.3