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Diffstat (limited to '')
| -rw-r--r-- | drivers/spi/spi-ppc4xx.c | 499 |
1 files changed, 499 insertions, 0 deletions
diff --git a/drivers/spi/spi-ppc4xx.c b/drivers/spi/spi-ppc4xx.c new file mode 100644 index 000000000..d65f047b6 --- /dev/null +++ b/drivers/spi/spi-ppc4xx.c @@ -0,0 +1,499 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * SPI_PPC4XX SPI controller driver. + * + * Copyright (C) 2007 Gary Jennejohn <garyj@denx.de> + * Copyright 2008 Stefan Roese <sr@denx.de>, DENX Software Engineering + * Copyright 2009 Harris Corporation, Steven A. Falco <sfalco@harris.com> + * + * Based in part on drivers/spi/spi_s3c24xx.c + * + * Copyright (c) 2006 Ben Dooks + * Copyright (c) 2006 Simtec Electronics + * Ben Dooks <ben@simtec.co.uk> + */ + +/* + * The PPC4xx SPI controller has no FIFO so each sent/received byte will + * generate an interrupt to the CPU. This can cause high CPU utilization. + * This driver allows platforms to reduce the interrupt load on the CPU + * during SPI transfers by setting max_speed_hz via the device tree. + */ + +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/errno.h> +#include <linux/wait.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/of_platform.h> +#include <linux/interrupt.h> +#include <linux/delay.h> + +#include <linux/spi/spi.h> +#include <linux/spi/spi_bitbang.h> + +#include <linux/io.h> +#include <asm/dcr.h> +#include <asm/dcr-regs.h> + +/* bits in mode register - bit 0 is MSb */ + +/* + * SPI_PPC4XX_MODE_SCP = 0 means "data latched on trailing edge of clock" + * SPI_PPC4XX_MODE_SCP = 1 means "data latched on leading edge of clock" + * Note: This is the inverse of CPHA. + */ +#define SPI_PPC4XX_MODE_SCP (0x80 >> 3) + +/* SPI_PPC4XX_MODE_SPE = 1 means "port enabled" */ +#define SPI_PPC4XX_MODE_SPE (0x80 >> 4) + +/* + * SPI_PPC4XX_MODE_RD = 0 means "MSB first" - this is the normal mode + * SPI_PPC4XX_MODE_RD = 1 means "LSB first" - this is bit-reversed mode + * Note: This is identical to SPI_LSB_FIRST. + */ +#define SPI_PPC4XX_MODE_RD (0x80 >> 5) + +/* + * SPI_PPC4XX_MODE_CI = 0 means "clock idles low" + * SPI_PPC4XX_MODE_CI = 1 means "clock idles high" + * Note: This is identical to CPOL. + */ +#define SPI_PPC4XX_MODE_CI (0x80 >> 6) + +/* + * SPI_PPC4XX_MODE_IL = 0 means "loopback disable" + * SPI_PPC4XX_MODE_IL = 1 means "loopback enable" + */ +#define SPI_PPC4XX_MODE_IL (0x80 >> 7) + +/* bits in control register */ +/* starts a transfer when set */ +#define SPI_PPC4XX_CR_STR (0x80 >> 7) + +/* bits in status register */ +/* port is busy with a transfer */ +#define SPI_PPC4XX_SR_BSY (0x80 >> 6) +/* RxD ready */ +#define SPI_PPC4XX_SR_RBR (0x80 >> 7) + +/* clock settings (SCP and CI) for various SPI modes */ +#define SPI_CLK_MODE0 (SPI_PPC4XX_MODE_SCP | 0) +#define SPI_CLK_MODE1 (0 | 0) +#define SPI_CLK_MODE2 (SPI_PPC4XX_MODE_SCP | SPI_PPC4XX_MODE_CI) +#define SPI_CLK_MODE3 (0 | SPI_PPC4XX_MODE_CI) + +#define DRIVER_NAME "spi_ppc4xx_of" + +struct spi_ppc4xx_regs { + u8 mode; + u8 rxd; + u8 txd; + u8 cr; + u8 sr; + u8 dummy; + /* + * Clock divisor modulus register + * This uses the following formula: + * SCPClkOut = OPBCLK/(4(CDM + 1)) + * or + * CDM = (OPBCLK/4*SCPClkOut) - 1 + * bit 0 is the MSb! + */ + u8 cdm; +}; + +/* SPI Controller driver's private data. */ +struct ppc4xx_spi { + /* bitbang has to be first */ + struct spi_bitbang bitbang; + struct completion done; + + u64 mapbase; + u64 mapsize; + int irqnum; + /* need this to set the SPI clock */ + unsigned int opb_freq; + + /* for transfers */ + int len; + int count; + /* data buffers */ + const unsigned char *tx; + unsigned char *rx; + + struct spi_ppc4xx_regs __iomem *regs; /* pointer to the registers */ + struct spi_master *master; + struct device *dev; +}; + +/* need this so we can set the clock in the chipselect routine */ +struct spi_ppc4xx_cs { + u8 mode; +}; + +static int spi_ppc4xx_txrx(struct spi_device *spi, struct spi_transfer *t) +{ + struct ppc4xx_spi *hw; + u8 data; + + dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n", + t->tx_buf, t->rx_buf, t->len); + + hw = spi_master_get_devdata(spi->master); + + hw->tx = t->tx_buf; + hw->rx = t->rx_buf; + hw->len = t->len; + hw->count = 0; + + /* send the first byte */ + data = hw->tx ? hw->tx[0] : 0; + out_8(&hw->regs->txd, data); + out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR); + wait_for_completion(&hw->done); + + return hw->count; +} + +static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t) +{ + struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master); + struct spi_ppc4xx_cs *cs = spi->controller_state; + int scr; + u8 cdm = 0; + u32 speed; + u8 bits_per_word; + + /* Start with the generic configuration for this device. */ + bits_per_word = spi->bits_per_word; + speed = spi->max_speed_hz; + + /* + * Modify the configuration if the transfer overrides it. Do not allow + * the transfer to overwrite the generic configuration with zeros. + */ + if (t) { + if (t->bits_per_word) + bits_per_word = t->bits_per_word; + + if (t->speed_hz) + speed = min(t->speed_hz, spi->max_speed_hz); + } + + if (!speed || (speed > spi->max_speed_hz)) { + dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed); + return -EINVAL; + } + + /* Write new configuration */ + out_8(&hw->regs->mode, cs->mode); + + /* Set the clock */ + /* opb_freq was already divided by 4 */ + scr = (hw->opb_freq / speed) - 1; + if (scr > 0) + cdm = min(scr, 0xff); + + dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", cdm, speed); + + if (in_8(&hw->regs->cdm) != cdm) + out_8(&hw->regs->cdm, cdm); + + mutex_lock(&hw->bitbang.lock); + if (!hw->bitbang.busy) { + hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE); + /* Need to ndelay here? */ + } + mutex_unlock(&hw->bitbang.lock); + + return 0; +} + +static int spi_ppc4xx_setup(struct spi_device *spi) +{ + struct spi_ppc4xx_cs *cs = spi->controller_state; + + if (!spi->max_speed_hz) { + dev_err(&spi->dev, "invalid max_speed_hz (must be non-zero)\n"); + return -EINVAL; + } + + if (cs == NULL) { + cs = kzalloc(sizeof(*cs), GFP_KERNEL); + if (!cs) + return -ENOMEM; + spi->controller_state = cs; + } + + /* + * We set all bits of the SPI0_MODE register, so, + * no need to read-modify-write + */ + cs->mode = SPI_PPC4XX_MODE_SPE; + + switch (spi->mode & SPI_MODE_X_MASK) { + case SPI_MODE_0: + cs->mode |= SPI_CLK_MODE0; + break; + case SPI_MODE_1: + cs->mode |= SPI_CLK_MODE1; + break; + case SPI_MODE_2: + cs->mode |= SPI_CLK_MODE2; + break; + case SPI_MODE_3: + cs->mode |= SPI_CLK_MODE3; + break; + } + + if (spi->mode & SPI_LSB_FIRST) + cs->mode |= SPI_PPC4XX_MODE_RD; + + return 0; +} + +static irqreturn_t spi_ppc4xx_int(int irq, void *dev_id) +{ + struct ppc4xx_spi *hw; + u8 status; + u8 data; + unsigned int count; + + hw = (struct ppc4xx_spi *)dev_id; + + status = in_8(&hw->regs->sr); + if (!status) + return IRQ_NONE; + + /* + * BSY de-asserts one cycle after the transfer is complete. The + * interrupt is asserted after the transfer is complete. The exact + * relationship is not documented, hence this code. + */ + + if (unlikely(status & SPI_PPC4XX_SR_BSY)) { + u8 lstatus; + int cnt = 0; + + dev_dbg(hw->dev, "got interrupt but spi still busy?\n"); + do { + ndelay(10); + lstatus = in_8(&hw->regs->sr); + } while (++cnt < 100 && lstatus & SPI_PPC4XX_SR_BSY); + + if (cnt >= 100) { + dev_err(hw->dev, "busywait: too many loops!\n"); + complete(&hw->done); + return IRQ_HANDLED; + } else { + /* status is always 1 (RBR) here */ + status = in_8(&hw->regs->sr); + dev_dbg(hw->dev, "loops %d status %x\n", cnt, status); + } + } + + count = hw->count; + hw->count++; + + /* RBR triggered this interrupt. Therefore, data must be ready. */ + data = in_8(&hw->regs->rxd); + if (hw->rx) + hw->rx[count] = data; + + count++; + + if (count < hw->len) { + data = hw->tx ? hw->tx[count] : 0; + out_8(&hw->regs->txd, data); + out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR); + } else { + complete(&hw->done); + } + + return IRQ_HANDLED; +} + +static void spi_ppc4xx_cleanup(struct spi_device *spi) +{ + kfree(spi->controller_state); +} + +static void spi_ppc4xx_enable(struct ppc4xx_spi *hw) +{ + /* + * On all 4xx PPC's the SPI bus is shared/multiplexed with + * the 2nd I2C bus. We need to enable the SPI bus before + * using it. + */ + + /* need to clear bit 14 to enable SPC */ + dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0); +} + +/* + * platform_device layer stuff... + */ +static int spi_ppc4xx_of_probe(struct platform_device *op) +{ + struct ppc4xx_spi *hw; + struct spi_master *master; + struct spi_bitbang *bbp; + struct resource resource; + struct device_node *np = op->dev.of_node; + struct device *dev = &op->dev; + struct device_node *opbnp; + int ret; + const unsigned int *clk; + + master = spi_alloc_master(dev, sizeof(*hw)); + if (master == NULL) + return -ENOMEM; + master->dev.of_node = np; + platform_set_drvdata(op, master); + hw = spi_master_get_devdata(master); + hw->master = master; + hw->dev = dev; + + init_completion(&hw->done); + + /* Setup the state for the bitbang driver */ + bbp = &hw->bitbang; + bbp->master = hw->master; + bbp->setup_transfer = spi_ppc4xx_setupxfer; + bbp->txrx_bufs = spi_ppc4xx_txrx; + bbp->use_dma = 0; + bbp->master->setup = spi_ppc4xx_setup; + bbp->master->cleanup = spi_ppc4xx_cleanup; + bbp->master->bits_per_word_mask = SPI_BPW_MASK(8); + bbp->master->use_gpio_descriptors = true; + /* + * The SPI core will count the number of GPIO descriptors to figure + * out the number of chip selects available on the platform. + */ + bbp->master->num_chipselect = 0; + + /* the spi->mode bits understood by this driver: */ + bbp->master->mode_bits = + SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST; + + /* Get the clock for the OPB */ + opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb"); + if (opbnp == NULL) { + dev_err(dev, "OPB: cannot find node\n"); + ret = -ENODEV; + goto free_master; + } + /* Get the clock (Hz) for the OPB */ + clk = of_get_property(opbnp, "clock-frequency", NULL); + if (clk == NULL) { + dev_err(dev, "OPB: no clock-frequency property set\n"); + of_node_put(opbnp); + ret = -ENODEV; + goto free_master; + } + hw->opb_freq = *clk; + hw->opb_freq >>= 2; + of_node_put(opbnp); + + ret = of_address_to_resource(np, 0, &resource); + if (ret) { + dev_err(dev, "error while parsing device node resource\n"); + goto free_master; + } + hw->mapbase = resource.start; + hw->mapsize = resource_size(&resource); + + /* Sanity check */ + if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) { + dev_err(dev, "too small to map registers\n"); + ret = -EINVAL; + goto free_master; + } + + /* Request IRQ */ + hw->irqnum = irq_of_parse_and_map(np, 0); + ret = request_irq(hw->irqnum, spi_ppc4xx_int, + 0, "spi_ppc4xx_of", (void *)hw); + if (ret) { + dev_err(dev, "unable to allocate interrupt\n"); + goto free_master; + } + + if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) { + dev_err(dev, "resource unavailable\n"); + ret = -EBUSY; + goto request_mem_error; + } + + hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs)); + + if (!hw->regs) { + dev_err(dev, "unable to memory map registers\n"); + ret = -ENXIO; + goto map_io_error; + } + + spi_ppc4xx_enable(hw); + + /* Finally register our spi controller */ + dev->dma_mask = 0; + ret = spi_bitbang_start(bbp); + if (ret) { + dev_err(dev, "failed to register SPI master\n"); + goto unmap_regs; + } + + dev_info(dev, "driver initialized\n"); + + return 0; + +unmap_regs: + iounmap(hw->regs); +map_io_error: + release_mem_region(hw->mapbase, hw->mapsize); +request_mem_error: + free_irq(hw->irqnum, hw); +free_master: + spi_master_put(master); + + dev_err(dev, "initialization failed\n"); + return ret; +} + +static int spi_ppc4xx_of_remove(struct platform_device *op) +{ + struct spi_master *master = platform_get_drvdata(op); + struct ppc4xx_spi *hw = spi_master_get_devdata(master); + + spi_bitbang_stop(&hw->bitbang); + release_mem_region(hw->mapbase, hw->mapsize); + free_irq(hw->irqnum, hw); + iounmap(hw->regs); + spi_master_put(master); + return 0; +} + +static const struct of_device_id spi_ppc4xx_of_match[] = { + { .compatible = "ibm,ppc4xx-spi", }, + {}, +}; + +MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match); + +static struct platform_driver spi_ppc4xx_of_driver = { + .probe = spi_ppc4xx_of_probe, + .remove = spi_ppc4xx_of_remove, + .driver = { + .name = DRIVER_NAME, + .of_match_table = spi_ppc4xx_of_match, + }, +}; +module_platform_driver(spi_ppc4xx_of_driver); + +MODULE_AUTHOR("Gary Jennejohn & Stefan Roese"); +MODULE_DESCRIPTION("Simple PPC4xx SPI Driver"); +MODULE_LICENSE("GPL"); |