| Message ID | c05f4d9abfdabb62b3b3cfeb57a3f9c138b4e45d.1433779081.git.cyrille.pitchen@atmel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Le 08/06/2015 18:07, Cyrille Pitchen a écrit : > This patch relies on the CSAAT (Chip Select Active After Transfer) feature > introduced by the version 2 of the spi controller. This new mode allows to > use properly the internal chip-select output pin of the spi controller > instead of using external gpios. Consequently, the "cs-gpios" device-tree > property becomes optional. > > When the new CSAAT bit is set into the Chip Select Register, the internal > chip-select output pin remains asserted till both the following conditions > become true: > - the LASTXFER bit is set into the Control Register (or the Transmit Data > Register) > - the Transmit Data Register and its shift register are empty. > > WARNING: if the LASTXFER bit is set into the Control Register then new > data are written into the Transmit Data Register fast enough to keep its > shifter not empty, the chip-select output pin remains asserted. Only when > the shifter becomes empty, the chip-select output pin is unasserted. > > When the CSAAT bit is clear in the Chip Select Register, the LASTXFER bit > is ignored in both the Control Register and the Transmit Data Register. > The internal chip-select output pin remains active as long as the Transmit > Data Register or its shift register are not empty. > > Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com> It seems okay: Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com> Thanks. Some additional changes might be needed: see below... > --- > drivers/spi/spi-atmel.c | 37 ++++++++++++++++++++++++++++--------- > 1 file changed, 28 insertions(+), 9 deletions(-) > > diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c > index a2f40b1..aa7d202 100644 > --- a/drivers/spi/spi-atmel.c > +++ b/drivers/spi/spi-atmel.c > @@ -246,6 +246,7 @@ struct atmel_spi { > > bool use_dma; > bool use_pdc; > + bool use_cs_gpios; > /* dmaengine data */ > struct atmel_spi_dma dma; > > @@ -321,7 +322,8 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi) > } > > mr = spi_readl(as, MR); > - gpio_set_value(asd->npcs_pin, active); > + if (as->use_cs_gpios) > + gpio_set_value(asd->npcs_pin, active); > } else { > u32 cpol = (spi->mode & SPI_CPOL) ? SPI_BIT(CPOL) : 0; > int i; > @@ -337,7 +339,7 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi) > > mr = spi_readl(as, MR); > mr = SPI_BFINS(PCS, ~(1 << spi->chip_select), mr); > - if (spi->chip_select != 0) > + if (as->use_cs_gpios && spi->chip_select != 0) > gpio_set_value(asd->npcs_pin, active); > spi_writel(as, MR, mr); > } Maybe in a debug function in cs_activate()... > @@ -366,7 +368,9 @@ static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi) > asd->npcs_pin, active ? " (low)" : "", > mr); > > - if (atmel_spi_is_v2(as) || spi->chip_select != 0) > + if (!as->use_cs_gpios) > + spi_writel(as, CR, SPI_BIT(LASTXFER)); > + else if (atmel_spi_is_v2(as) || spi->chip_select != 0) > gpio_set_value(asd->npcs_pin, !active); > } > ... as well as in cs_deactivate(), you need to change the use of asd->npcs_pin: dev_dbg(&spi->dev, "activate %u%s, mr %08x\n", asd->npcs_pin, active ? " (high)" : "", mr); so that it is still relevant in the !as->use_cs_gpios case... Bye, > @@ -996,6 +1000,8 @@ static int atmel_spi_setup(struct spi_device *spi) > csr |= SPI_BIT(CPOL); > if (!(spi->mode & SPI_CPHA)) > csr |= SPI_BIT(NCPHA); > + if (!as->use_cs_gpios) > + csr |= SPI_BIT(CSAAT); > > /* DLYBS is mostly irrelevant since we manage chipselect using GPIOs. > * > @@ -1009,7 +1015,9 @@ static int atmel_spi_setup(struct spi_device *spi) > /* chipselect must have been muxed as GPIO (e.g. in board setup) */ > npcs_pin = (unsigned long)spi->controller_data; > > - if (gpio_is_valid(spi->cs_gpio)) > + if (!as->use_cs_gpios) > + npcs_pin = spi->chip_select; > + else if (gpio_is_valid(spi->cs_gpio)) > npcs_pin = spi->cs_gpio; > > asd = spi->controller_state; > @@ -1018,15 +1026,19 @@ static int atmel_spi_setup(struct spi_device *spi) > if (!asd) > return -ENOMEM; > > - ret = gpio_request(npcs_pin, dev_name(&spi->dev)); > - if (ret) { > - kfree(asd); > - return ret; > + if (as->use_cs_gpios) { > + ret = gpio_request(npcs_pin, dev_name(&spi->dev)); > + if (ret) { > + kfree(asd); > + return ret; > + } > + > + gpio_direction_output(npcs_pin, > + !(spi->mode & SPI_CS_HIGH)); > } > > asd->npcs_pin = npcs_pin; > spi->controller_state = asd; > - gpio_direction_output(npcs_pin, !(spi->mode & SPI_CS_HIGH)); > } > > asd->csr = csr; > @@ -1338,6 +1350,13 @@ static int atmel_spi_probe(struct platform_device *pdev) > > atmel_get_caps(as); > > + as->use_cs_gpios = true; > + if (atmel_spi_is_v2(as) && > + !of_get_property(pdev->dev.of_node, "cs-gpios", NULL)) { > + as->use_cs_gpios = false; > + master->num_chipselect = 4; > + } > + > as->use_dma = false; > as->use_pdc = false; > if (as->caps.has_dma_support) { >
diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index a2f40b1..aa7d202 100644 --- a/drivers/spi/spi-atmel.c +++ b/drivers/spi/spi-atmel.c @@ -246,6 +246,7 @@ struct atmel_spi { bool use_dma; bool use_pdc; + bool use_cs_gpios; /* dmaengine data */ struct atmel_spi_dma dma; @@ -321,7 +322,8 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi) } mr = spi_readl(as, MR); - gpio_set_value(asd->npcs_pin, active); + if (as->use_cs_gpios) + gpio_set_value(asd->npcs_pin, active); } else { u32 cpol = (spi->mode & SPI_CPOL) ? SPI_BIT(CPOL) : 0; int i; @@ -337,7 +339,7 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi) mr = spi_readl(as, MR); mr = SPI_BFINS(PCS, ~(1 << spi->chip_select), mr); - if (spi->chip_select != 0) + if (as->use_cs_gpios && spi->chip_select != 0) gpio_set_value(asd->npcs_pin, active); spi_writel(as, MR, mr); } @@ -366,7 +368,9 @@ static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi) asd->npcs_pin, active ? " (low)" : "", mr); - if (atmel_spi_is_v2(as) || spi->chip_select != 0) + if (!as->use_cs_gpios) + spi_writel(as, CR, SPI_BIT(LASTXFER)); + else if (atmel_spi_is_v2(as) || spi->chip_select != 0) gpio_set_value(asd->npcs_pin, !active); } @@ -996,6 +1000,8 @@ static int atmel_spi_setup(struct spi_device *spi) csr |= SPI_BIT(CPOL); if (!(spi->mode & SPI_CPHA)) csr |= SPI_BIT(NCPHA); + if (!as->use_cs_gpios) + csr |= SPI_BIT(CSAAT); /* DLYBS is mostly irrelevant since we manage chipselect using GPIOs. * @@ -1009,7 +1015,9 @@ static int atmel_spi_setup(struct spi_device *spi) /* chipselect must have been muxed as GPIO (e.g. in board setup) */ npcs_pin = (unsigned long)spi->controller_data; - if (gpio_is_valid(spi->cs_gpio)) + if (!as->use_cs_gpios) + npcs_pin = spi->chip_select; + else if (gpio_is_valid(spi->cs_gpio)) npcs_pin = spi->cs_gpio; asd = spi->controller_state; @@ -1018,15 +1026,19 @@ static int atmel_spi_setup(struct spi_device *spi) if (!asd) return -ENOMEM; - ret = gpio_request(npcs_pin, dev_name(&spi->dev)); - if (ret) { - kfree(asd); - return ret; + if (as->use_cs_gpios) { + ret = gpio_request(npcs_pin, dev_name(&spi->dev)); + if (ret) { + kfree(asd); + return ret; + } + + gpio_direction_output(npcs_pin, + !(spi->mode & SPI_CS_HIGH)); } asd->npcs_pin = npcs_pin; spi->controller_state = asd; - gpio_direction_output(npcs_pin, !(spi->mode & SPI_CS_HIGH)); } asd->csr = csr; @@ -1338,6 +1350,13 @@ static int atmel_spi_probe(struct platform_device *pdev) atmel_get_caps(as); + as->use_cs_gpios = true; + if (atmel_spi_is_v2(as) && + !of_get_property(pdev->dev.of_node, "cs-gpios", NULL)) { + as->use_cs_gpios = false; + master->num_chipselect = 4; + } + as->use_dma = false; as->use_pdc = false; if (as->caps.has_dma_support) {
This patch relies on the CSAAT (Chip Select Active After Transfer) feature introduced by the version 2 of the spi controller. This new mode allows to use properly the internal chip-select output pin of the spi controller instead of using external gpios. Consequently, the "cs-gpios" device-tree property becomes optional. When the new CSAAT bit is set into the Chip Select Register, the internal chip-select output pin remains asserted till both the following conditions become true: - the LASTXFER bit is set into the Control Register (or the Transmit Data Register) - the Transmit Data Register and its shift register are empty. WARNING: if the LASTXFER bit is set into the Control Register then new data are written into the Transmit Data Register fast enough to keep its shifter not empty, the chip-select output pin remains asserted. Only when the shifter becomes empty, the chip-select output pin is unasserted. When the CSAAT bit is clear in the Chip Select Register, the LASTXFER bit is ignored in both the Control Register and the Transmit Data Register. The internal chip-select output pin remains active as long as the Transmit Data Register or its shift register are not empty. Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com> --- drivers/spi/spi-atmel.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-)