diff options
| -rw-r--r-- | drivers/spi/spi-bcm2835.c | 212 |
1 files changed, 124 insertions, 88 deletions
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index 3f93718aad3f..0dbe544e8be4 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -3,6 +3,7 @@ * * Copyright (C) 2012 Chris Boot * Copyright (C) 2013 Stephen Warren + * Copyright (C) 2015 Martin Sperl * * This driver is inspired by: * spi-ath79.c, Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org> @@ -29,6 +30,7 @@ #include <linux/module.h> #include <linux/of.h> #include <linux/of_irq.h> +#include <linux/of_gpio.h> #include <linux/of_device.h> #include <linux/spi/spi.h> @@ -76,10 +78,10 @@ struct bcm2835_spi { void __iomem *regs; struct clk *clk; int irq; - struct completion done; const u8 *tx_buf; u8 *rx_buf; - int len; + int tx_len; + int rx_len; }; static inline u32 bcm2835_rd(struct bcm2835_spi *bs, unsigned reg) @@ -96,10 +98,12 @@ static inline void bcm2835_rd_fifo(struct bcm2835_spi *bs) { u8 byte; - while (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_RXD) { + while ((bs->rx_len) && + (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_RXD)) { byte = bcm2835_rd(bs, BCM2835_SPI_FIFO); if (bs->rx_buf) *bs->rx_buf++ = byte; + bs->rx_len--; } } @@ -107,47 +111,60 @@ static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs) { u8 byte; - while ((bs->len) && + while ((bs->tx_len) && (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_TXD)) { byte = bs->tx_buf ? *bs->tx_buf++ : 0; bcm2835_wr(bs, BCM2835_SPI_FIFO, byte); - bs->len--; + bs->tx_len--; } } +static void bcm2835_spi_reset_hw(struct spi_master *master) +{ + struct bcm2835_spi *bs = spi_master_get_devdata(master); + u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); + + /* Disable SPI interrupts and transfer */ + cs &= ~(BCM2835_SPI_CS_INTR | + BCM2835_SPI_CS_INTD | + BCM2835_SPI_CS_TA); + /* and reset RX/TX FIFOS */ + cs |= BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX; + + /* and reset the SPI_HW */ + bcm2835_wr(bs, BCM2835_SPI_CS, cs); +} + static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) { struct spi_master *master = dev_id; struct bcm2835_spi *bs = spi_master_get_devdata(master); - u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); /* Read as many bytes as possible from FIFO */ bcm2835_rd_fifo(bs); - - if (bs->len) { /* there is more data to transmit */ - bcm2835_wr_fifo(bs); - } else { /* Transfer complete */ - /* Disable SPI interrupts */ - cs &= ~(BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD); - bcm2835_wr(bs, BCM2835_SPI_CS, cs); - - /* - * Wake up bcm2835_spi_transfer_one(), which will call - * bcm2835_spi_finish_transfer(), to drain the RX FIFO. - */ - complete(&bs->done); + /* Write as many bytes as possible to FIFO */ + bcm2835_wr_fifo(bs); + + /* based on flags decide if we can finish the transfer */ + if (bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_DONE) { + /* Transfer complete - reset SPI HW */ + bcm2835_spi_reset_hw(master); + /* wake up the framework */ + complete(&master->xfer_completion); } return IRQ_HANDLED; } -static int bcm2835_spi_start_transfer(struct spi_device *spi, - struct spi_transfer *tfr) +static int bcm2835_spi_transfer_one(struct spi_master *master, + struct spi_device *spi, + struct spi_transfer *tfr) { - struct bcm2835_spi *bs = spi_master_get_devdata(spi->master); + struct bcm2835_spi *bs = spi_master_get_devdata(master); unsigned long spi_hz, clk_hz, cdiv; - u32 cs = BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA; + u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); + /* set clock */ spi_hz = tfr->speed_hz; clk_hz = clk_get_rate(bs->clk); @@ -163,100 +180,118 @@ static int bcm2835_spi_start_transfer(struct spi_device *spi, } else { cdiv = 0; /* 0 is the slowest we can go */ } + bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv); + /* handle all the modes */ if ((spi->mode & SPI_3WIRE) && (tfr->rx_buf)) cs |= BCM2835_SPI_CS_REN; - if (spi->mode & SPI_CPOL) cs |= BCM2835_SPI_CS_CPOL; if (spi->mode & SPI_CPHA) cs |= BCM2835_SPI_CS_CPHA; - if (!(spi->mode & SPI_NO_CS)) { - if (spi->mode & SPI_CS_HIGH) { - cs |= BCM2835_SPI_CS_CSPOL; - cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select; - } - - cs |= spi->chip_select; - } + /* for gpio_cs set dummy CS so that no HW-CS get changed + * we can not run this in bcm2835_spi_set_cs, as it does + * not get called for cs_gpio cases, so we need to do it here + */ + if (gpio_is_valid(spi->cs_gpio) || (spi->mode & SPI_NO_CS)) + cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01; - reinit_completion(&bs->done); + /* set transmit buffers and length */ bs->tx_buf = tfr->tx_buf; bs->rx_buf = tfr->rx_buf; - bs->len = tfr->len; + bs->tx_len = tfr->len; + bs->rx_len = tfr->len; - bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv); /* * Enable the HW block. This will immediately trigger a DONE (TX * empty) interrupt, upon which we will fill the TX FIFO with the * first TX bytes. Pre-filling the TX FIFO here to avoid the * interrupt doesn't work:-( */ + cs |= BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA; bcm2835_wr(bs, BCM2835_SPI_CS, cs); - return 0; + /* signal that we need to wait for completion */ + return 1; } -static int bcm2835_spi_finish_transfer(struct spi_device *spi, - struct spi_transfer *tfr, - bool cs_change) +static void bcm2835_spi_handle_err(struct spi_master *master, + struct spi_message *msg) { - struct bcm2835_spi *bs = spi_master_get_devdata(spi->master); - u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); - - if (tfr->delay_usecs) - udelay(tfr->delay_usecs); - - if (cs_change) - /* Clear TA flag */ - bcm2835_wr(bs, BCM2835_SPI_CS, cs & ~BCM2835_SPI_CS_TA); - - return 0; + bcm2835_spi_reset_hw(master); } -static int bcm2835_spi_transfer_one(struct spi_master *master, - struct spi_message *mesg) +static void bcm2835_spi_set_cs(struct spi_device *spi, bool gpio_level) { + /* + * we can assume that we are "native" as per spi_set_cs + * calling us ONLY when cs_gpio is not set + * we can also assume that we are CS < 3 as per bcm2835_spi_setup + * we would not get called because of error handling there. + * the level passed is the electrical level not enabled/disabled + * so it has to get translated back to enable/disable + * see spi_set_cs in spi.c for the implementation + */ + + struct spi_master *master = spi->master; struct bcm2835_spi *bs = spi_master_get_devdata(master); - struct spi_transfer *tfr; - struct spi_device *spi = mesg->spi; - int err = 0; - unsigned int timeout; - bool cs_change; - - list_for_each_entry(tfr, &mesg->transfers, transfer_list) { - err = bcm2835_spi_start_transfer(spi, tfr); - if (err) - goto out; - - timeout = wait_for_completion_timeout( - &bs->done, - msecs_to_jiffies(BCM2835_SPI_TIMEOUT_MS) - ); - if (!timeout) { - err = -ETIMEDOUT; - goto out; - } + u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); + bool enable; - cs_change = tfr->cs_change || - list_is_last(&tfr->transfer_list, &mesg->transfers); + /* calculate the enable flag from the passed gpio_level */ + enable = (spi->mode & SPI_CS_HIGH) ? gpio_level : !gpio_level; - err = bcm2835_spi_finish_transfer(spi, tfr, cs_change); - if (err) - goto out; + /* set flags for "reverse" polarity in the registers */ + if (spi->mode & SPI_CS_HIGH) { + /* set the correct CS-bits */ + cs |= BCM2835_SPI_CS_CSPOL; + cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select; + } else { + /* clean the CS-bits */ + cs &= ~BCM2835_SPI_CS_CSPOL; + cs &= ~(BCM2835_SPI_CS_CSPOL0 << spi->chip_select); + } - mesg->actual_length += (tfr->len - bs->len); + /* select the correct chip_select depending on disabled/enabled */ + if (enable) { + /* set cs correctly */ + if (spi->mode & SPI_NO_CS) { + /* use the "undefined" chip-select */ + cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01; + } else { + /* set the chip select */ + cs &= ~(BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01); + cs |= spi->chip_select; + } + } else { + /* disable CSPOL which puts HW-CS into deselected state */ + cs &= ~BCM2835_SPI_CS_CSPOL; + /* use the "undefined" chip-select as precaution */ + cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01; } -out: - /* Clear FIFOs, and disable the HW block */ - bcm2835_wr(bs, BCM2835_SPI_CS, - BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX); - mesg->status = err; - spi_finalize_current_message(master); + /* finally set the calculated flags in SPI_CS */ + bcm2835_wr(bs, BCM2835_SPI_CS, cs); +} - return 0; +static int bcm2835_spi_setup(struct spi_device *spi) +{ + /* + * sanity checking the native-chipselects + */ + if (spi->mode & SPI_NO_CS) + return 0; + if (gpio_is_valid(spi->cs_gpio)) + return 0; + if (spi->chip_select < 3) + return 0; + + /* error in the case of native CS requested with CS-id > 2 */ + dev_err(&spi->dev, + "setup: only three native chip-selects are supported\n" + ); + return -EINVAL; } static int bcm2835_spi_probe(struct platform_device *pdev) @@ -277,13 +312,14 @@ static int bcm2835_spi_probe(struct platform_device *pdev) master->mode_bits = BCM2835_SPI_MODE_BITS; master->bits_per_word_mask = SPI_BPW_MASK(8); master->num_chipselect = 3; - master->transfer_one_message = bcm2835_spi_transfer_one; + master->setup = bcm2835_spi_setup; + master->set_cs = bcm2835_spi_set_cs; + master->transfer_one = bcm2835_spi_transfer_one; + master->handle_err = bcm2835_spi_handle_err; master->dev.of_node = pdev->dev.of_node; bs = spi_master_get_devdata(master); - init_completion(&bs->done); - res = platform_get_resource(pdev, IORESOURCE_MEM, 0); bs->regs = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(bs->regs)) { @@ -314,7 +350,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) goto out_clk_disable; } - /* initialise the hardware */ + /* initialise the hardware with the default polarities */ bcm2835_wr(bs, BCM2835_SPI_CS, BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX); |