// SPDX-License-Identifier: GPL-2.0-only /* * SPI_PPC4XX SPI controller driver. * * Copyright (C) 2007 Gary Jennejohn * Copyright 2008 Stefan Roese , DENX Software Engineering * Copyright 2009 Harris Corporation, Steven A. Falco * * Based in part on drivers/spi/spi_s3c24xx.c * * Copyright (c) 2006 Ben Dooks * Copyright (c) 2006 Simtec Electronics * Ben Dooks */ /* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* 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_controller *host; 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_controller_get_devdata(spi->controller); 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_controller_get_devdata(spi->controller); struct spi_ppc4xx_cs *cs = spi->controller_state; int scr; u8 cdm = 0; u32 speed; /* Start with the generic configuration for this device. */ 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->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_controller *host; 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; host = spi_alloc_host(dev, sizeof(*hw)); if (host == NULL) return -ENOMEM; host->dev.of_node = np; platform_set_drvdata(op, host); hw = spi_controller_get_devdata(host); hw->host = host; hw->dev = dev; init_completion(&hw->done); /* Setup the state for the bitbang driver */ bbp = &hw->bitbang; bbp->master = hw->host; 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_host; } /* 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_host; } 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_host; } 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_host; } /* 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_host; } 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 host\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_host: spi_controller_put(host); dev_err(dev, "initialization failed\n"); return ret; } static void spi_ppc4xx_of_remove(struct platform_device *op) { struct spi_controller *host = platform_get_drvdata(op); struct ppc4xx_spi *hw = spi_controller_get_devdata(host); spi_bitbang_stop(&hw->bitbang); release_mem_region(hw->mapbase, hw->mapsize); free_irq(hw->irqnum, hw); iounmap(hw->regs); spi_controller_put(host); } 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_new = 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");