/* * 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> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published * by the Free Software Foundation. */ /* * 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/init.h> #include <linux/sched.h> #include <linux/errno.h> #include <linux/wait.h> #include <linux/of_platform.h> #include <linux/of_spi.h> #include <linux/of_gpio.h> #include <linux/interrupt.h> #include <linux/delay.h> #include <linux/gpio.h> #include <linux/spi/spi.h> #include <linux/spi/spi_bitbang.h> #include <asm/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 follwing 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; int *gpios; 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 (bits_per_word != 8) { dev_err(&spi->dev, "invalid bits-per-word (%d)\n", bits_per_word); return -EINVAL; } if (!speed || (speed > spi->max_speed_hz)) { dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed); return -EINVAL; } /* Write new configration */ 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); spin_lock(&hw->bitbang.lock); if (!hw->bitbang.busy) { hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE); /* Need to ndelay here? */ } spin_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->bits_per_word != 8) { dev_err(&spi->dev, "invalid bits-per-word (%d)\n", spi->bits_per_word); return -EINVAL; } 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_CPHA | SPI_CPOL)) { 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 void spi_ppc4xx_chipsel(struct spi_device *spi, int value) { struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master); unsigned int cs = spi->chip_select; unsigned int cspol; /* * If there are no chip selects at all, or if this is the special * case of a non-existent (dummy) chip select, do nothing. */ if (!hw->master->num_chipselect || hw->gpios[cs] == -EEXIST) return; cspol = spi->mode & SPI_CS_HIGH ? 1 : 0; if (value == BITBANG_CS_INACTIVE) cspol = !cspol; gpio_set_value(hw->gpios[cs], cspol); } 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 the SPI bus before * using it. */ /* need to clear bit 14 to enable SPC */ dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0); } static void free_gpios(struct ppc4xx_spi *hw) { if (hw->master->num_chipselect) { int i; for (i = 0; i < hw->master->num_chipselect; i++) if (gpio_is_valid(hw->gpios[i])) gpio_free(hw->gpios[i]); kfree(hw->gpios); hw->gpios = NULL; } } /* * of_device layer stuff... */ static int __init spi_ppc4xx_of_probe(struct of_device *op, const struct of_device_id *match) { struct ppc4xx_spi *hw; struct spi_master *master; struct spi_bitbang *bbp; struct resource resource; struct device_node *np = op->node; struct device *dev = &op->dev; struct device_node *opbnp; int ret; int num_gpios; const unsigned int *clk; master = spi_alloc_master(dev, sizeof *hw); if (master == NULL) return -ENOMEM; dev_set_drvdata(dev, master); hw = spi_master_get_devdata(master); hw->master = spi_master_get(master); hw->dev = dev; init_completion(&hw->done); /* * A count of zero implies a single SPI device without any chip-select. * Note that of_gpio_count counts all gpios assigned to this spi master. * This includes both "null" gpio's and real ones. */ num_gpios = of_gpio_count(np); if (num_gpios) { int i; hw->gpios = kzalloc(sizeof(int) * num_gpios, GFP_KERNEL); if (!hw->gpios) { ret = -ENOMEM; goto free_master; } for (i = 0; i < num_gpios; i++) { int gpio; enum of_gpio_flags flags; gpio = of_get_gpio_flags(np, i, &flags); hw->gpios[i] = gpio; if (gpio_is_valid(gpio)) { /* Real CS - set the initial state. */ ret = gpio_request(gpio, np->name); if (ret < 0) { dev_err(dev, "can't request gpio " "#%d: %d\n", i, ret); goto free_gpios; } gpio_direction_output(gpio, !!(flags & OF_GPIO_ACTIVE_LOW)); } else if (gpio == -EEXIST) { ; /* No CS, but that's OK. */ } else { dev_err(dev, "invalid gpio #%d: %d\n", i, gpio); ret = -EINVAL; goto free_gpios; } } } /* Setup the state for the bitbang driver */ bbp = &hw->bitbang; bbp->master = hw->master; bbp->setup_transfer = spi_ppc4xx_setupxfer; bbp->chipselect = spi_ppc4xx_chipsel; bbp->txrx_bufs = spi_ppc4xx_txrx; bbp->use_dma = 0; bbp->master->setup = spi_ppc4xx_setup; bbp->master->cleanup = spi_ppc4xx_cleanup; /* Allocate bus num dynamically. */ bbp->master->bus_num = -1; /* the spi->mode bits understood by this driver: */ bbp->master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST; /* this many pins in all GPIO controllers */ bbp->master->num_chipselect = num_gpios; /* 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_gpios; } /* 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_gpios; } 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_gpios; } hw->mapbase = resource.start; hw->mapsize = resource.end - resource.start + 1; /* Sanity check */ if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) { dev_err(dev, "too small to map registers\n"); ret = -EINVAL; goto free_gpios; } /* Request IRQ */ hw->irqnum = irq_of_parse_and_map(np, 0); ret = request_irq(hw->irqnum, spi_ppc4xx_int, IRQF_DISABLED, "spi_ppc4xx_of", (void *)hw); if (ret) { dev_err(dev, "unable to allocate interrupt\n"); goto free_gpios; } 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"); of_register_spi_devices(master, np); 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_gpios: free_gpios(hw); free_master: dev_set_drvdata(dev, NULL); spi_master_put(master); dev_err(dev, "initialization failed\n"); return ret; } static int __exit spi_ppc4xx_of_remove(struct of_device *op) { struct spi_master *master = dev_get_drvdata(&op->dev); struct ppc4xx_spi *hw = spi_master_get_devdata(master); spi_bitbang_stop(&hw->bitbang); dev_set_drvdata(&op->dev, NULL); release_mem_region(hw->mapbase, hw->mapsize); free_irq(hw->irqnum, hw); iounmap(hw->regs); free_gpios(hw); return 0; } static struct of_device_id spi_ppc4xx_of_match[] = { { .compatible = "ibm,ppc4xx-spi", }, {}, }; MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match); static struct of_platform_driver spi_ppc4xx_of_driver = { .match_table = spi_ppc4xx_of_match, .probe = spi_ppc4xx_of_probe, .remove = __exit_p(spi_ppc4xx_of_remove), .driver = { .name = DRIVER_NAME, .owner = THIS_MODULE, }, }; static int __init spi_ppc4xx_init(void) { return of_register_platform_driver(&spi_ppc4xx_of_driver); } module_init(spi_ppc4xx_init); static void __exit spi_ppc4xx_exit(void) { of_unregister_platform_driver(&spi_ppc4xx_of_driver); } module_exit(spi_ppc4xx_exit); MODULE_AUTHOR("Gary Jennejohn & Stefan Roese"); MODULE_DESCRIPTION("Simple PPC4xx SPI Driver"); MODULE_LICENSE("GPL");