diff options
Diffstat (limited to 'drivers/spi/spi-ep93xx.c')
| -rw-r--r-- | drivers/spi/spi-ep93xx.c | 761 |
1 files changed, 761 insertions, 0 deletions
diff --git a/drivers/spi/spi-ep93xx.c b/drivers/spi/spi-ep93xx.c new file mode 100644 index 0000000000..a1d60e51c0 --- /dev/null +++ b/drivers/spi/spi-ep93xx.c @@ -0,0 +1,761 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Driver for Cirrus Logic EP93xx SPI controller. + * + * Copyright (C) 2010-2011 Mika Westerberg + * + * Explicit FIFO handling code was inspired by amba-pl022 driver. + * + * Chip select support using other than built-in GPIOs by H. Hartley Sweeten. + * + * For more information about the SPI controller see documentation on Cirrus + * Logic web site: + * https://www.cirrus.com/en/pubs/manual/EP93xx_Users_Guide_UM1.pdf + */ + +#include <linux/io.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/dmaengine.h> +#include <linux/bitops.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/sched.h> +#include <linux/scatterlist.h> +#include <linux/spi/spi.h> + +#include <linux/platform_data/dma-ep93xx.h> +#include <linux/platform_data/spi-ep93xx.h> + +#define SSPCR0 0x0000 +#define SSPCR0_SPO BIT(6) +#define SSPCR0_SPH BIT(7) +#define SSPCR0_SCR_SHIFT 8 + +#define SSPCR1 0x0004 +#define SSPCR1_RIE BIT(0) +#define SSPCR1_TIE BIT(1) +#define SSPCR1_RORIE BIT(2) +#define SSPCR1_LBM BIT(3) +#define SSPCR1_SSE BIT(4) +#define SSPCR1_MS BIT(5) +#define SSPCR1_SOD BIT(6) + +#define SSPDR 0x0008 + +#define SSPSR 0x000c +#define SSPSR_TFE BIT(0) +#define SSPSR_TNF BIT(1) +#define SSPSR_RNE BIT(2) +#define SSPSR_RFF BIT(3) +#define SSPSR_BSY BIT(4) +#define SSPCPSR 0x0010 + +#define SSPIIR 0x0014 +#define SSPIIR_RIS BIT(0) +#define SSPIIR_TIS BIT(1) +#define SSPIIR_RORIS BIT(2) +#define SSPICR SSPIIR + +/* timeout in milliseconds */ +#define SPI_TIMEOUT 5 +/* maximum depth of RX/TX FIFO */ +#define SPI_FIFO_SIZE 8 + +/** + * struct ep93xx_spi - EP93xx SPI controller structure + * @clk: clock for the controller + * @mmio: pointer to ioremap()'d registers + * @sspdr_phys: physical address of the SSPDR register + * @tx: current byte in transfer to transmit + * @rx: current byte in transfer to receive + * @fifo_level: how full is FIFO (%0..%SPI_FIFO_SIZE - %1). Receiving one + * frame decreases this level and sending one frame increases it. + * @dma_rx: RX DMA channel + * @dma_tx: TX DMA channel + * @dma_rx_data: RX parameters passed to the DMA engine + * @dma_tx_data: TX parameters passed to the DMA engine + * @rx_sgt: sg table for RX transfers + * @tx_sgt: sg table for TX transfers + * @zeropage: dummy page used as RX buffer when only TX buffer is passed in by + * the client + */ +struct ep93xx_spi { + struct clk *clk; + void __iomem *mmio; + unsigned long sspdr_phys; + size_t tx; + size_t rx; + size_t fifo_level; + struct dma_chan *dma_rx; + struct dma_chan *dma_tx; + struct ep93xx_dma_data dma_rx_data; + struct ep93xx_dma_data dma_tx_data; + struct sg_table rx_sgt; + struct sg_table tx_sgt; + void *zeropage; +}; + +/* converts bits per word to CR0.DSS value */ +#define bits_per_word_to_dss(bpw) ((bpw) - 1) + +/** + * ep93xx_spi_calc_divisors() - calculates SPI clock divisors + * @host: SPI host + * @rate: desired SPI output clock rate + * @div_cpsr: pointer to return the cpsr (pre-scaler) divider + * @div_scr: pointer to return the scr divider + */ +static int ep93xx_spi_calc_divisors(struct spi_controller *host, + u32 rate, u8 *div_cpsr, u8 *div_scr) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + unsigned long spi_clk_rate = clk_get_rate(espi->clk); + int cpsr, scr; + + /* + * Make sure that max value is between values supported by the + * controller. + */ + rate = clamp(rate, host->min_speed_hz, host->max_speed_hz); + + /* + * Calculate divisors so that we can get speed according the + * following formula: + * rate = spi_clock_rate / (cpsr * (1 + scr)) + * + * cpsr must be even number and starts from 2, scr can be any number + * between 0 and 255. + */ + for (cpsr = 2; cpsr <= 254; cpsr += 2) { + for (scr = 0; scr <= 255; scr++) { + if ((spi_clk_rate / (cpsr * (scr + 1))) <= rate) { + *div_scr = (u8)scr; + *div_cpsr = (u8)cpsr; + return 0; + } + } + } + + return -EINVAL; +} + +static int ep93xx_spi_chip_setup(struct spi_controller *host, + struct spi_device *spi, + struct spi_transfer *xfer) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + u8 dss = bits_per_word_to_dss(xfer->bits_per_word); + u8 div_cpsr = 0; + u8 div_scr = 0; + u16 cr0; + int err; + + err = ep93xx_spi_calc_divisors(host, xfer->speed_hz, + &div_cpsr, &div_scr); + if (err) + return err; + + cr0 = div_scr << SSPCR0_SCR_SHIFT; + if (spi->mode & SPI_CPOL) + cr0 |= SSPCR0_SPO; + if (spi->mode & SPI_CPHA) + cr0 |= SSPCR0_SPH; + cr0 |= dss; + + dev_dbg(&host->dev, "setup: mode %d, cpsr %d, scr %d, dss %d\n", + spi->mode, div_cpsr, div_scr, dss); + dev_dbg(&host->dev, "setup: cr0 %#x\n", cr0); + + writel(div_cpsr, espi->mmio + SSPCPSR); + writel(cr0, espi->mmio + SSPCR0); + + return 0; +} + +static void ep93xx_do_write(struct spi_controller *host) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + struct spi_transfer *xfer = host->cur_msg->state; + u32 val = 0; + + if (xfer->bits_per_word > 8) { + if (xfer->tx_buf) + val = ((u16 *)xfer->tx_buf)[espi->tx]; + espi->tx += 2; + } else { + if (xfer->tx_buf) + val = ((u8 *)xfer->tx_buf)[espi->tx]; + espi->tx += 1; + } + writel(val, espi->mmio + SSPDR); +} + +static void ep93xx_do_read(struct spi_controller *host) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + struct spi_transfer *xfer = host->cur_msg->state; + u32 val; + + val = readl(espi->mmio + SSPDR); + if (xfer->bits_per_word > 8) { + if (xfer->rx_buf) + ((u16 *)xfer->rx_buf)[espi->rx] = val; + espi->rx += 2; + } else { + if (xfer->rx_buf) + ((u8 *)xfer->rx_buf)[espi->rx] = val; + espi->rx += 1; + } +} + +/** + * ep93xx_spi_read_write() - perform next RX/TX transfer + * @host: SPI host + * + * This function transfers next bytes (or half-words) to/from RX/TX FIFOs. If + * called several times, the whole transfer will be completed. Returns + * %-EINPROGRESS when current transfer was not yet completed otherwise %0. + * + * When this function is finished, RX FIFO should be empty and TX FIFO should be + * full. + */ +static int ep93xx_spi_read_write(struct spi_controller *host) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + struct spi_transfer *xfer = host->cur_msg->state; + + /* read as long as RX FIFO has frames in it */ + while ((readl(espi->mmio + SSPSR) & SSPSR_RNE)) { + ep93xx_do_read(host); + espi->fifo_level--; + } + + /* write as long as TX FIFO has room */ + while (espi->fifo_level < SPI_FIFO_SIZE && espi->tx < xfer->len) { + ep93xx_do_write(host); + espi->fifo_level++; + } + + if (espi->rx == xfer->len) + return 0; + + return -EINPROGRESS; +} + +static enum dma_transfer_direction +ep93xx_dma_data_to_trans_dir(enum dma_data_direction dir) +{ + switch (dir) { + case DMA_TO_DEVICE: + return DMA_MEM_TO_DEV; + case DMA_FROM_DEVICE: + return DMA_DEV_TO_MEM; + default: + return DMA_TRANS_NONE; + } +} + +/** + * ep93xx_spi_dma_prepare() - prepares a DMA transfer + * @host: SPI host + * @dir: DMA transfer direction + * + * Function configures the DMA, maps the buffer and prepares the DMA + * descriptor. Returns a valid DMA descriptor in case of success and ERR_PTR + * in case of failure. + */ +static struct dma_async_tx_descriptor * +ep93xx_spi_dma_prepare(struct spi_controller *host, + enum dma_data_direction dir) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + struct spi_transfer *xfer = host->cur_msg->state; + struct dma_async_tx_descriptor *txd; + enum dma_slave_buswidth buswidth; + struct dma_slave_config conf; + struct scatterlist *sg; + struct sg_table *sgt; + struct dma_chan *chan; + const void *buf, *pbuf; + size_t len = xfer->len; + int i, ret, nents; + + if (xfer->bits_per_word > 8) + buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES; + else + buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE; + + memset(&conf, 0, sizeof(conf)); + conf.direction = ep93xx_dma_data_to_trans_dir(dir); + + if (dir == DMA_FROM_DEVICE) { + chan = espi->dma_rx; + buf = xfer->rx_buf; + sgt = &espi->rx_sgt; + + conf.src_addr = espi->sspdr_phys; + conf.src_addr_width = buswidth; + } else { + chan = espi->dma_tx; + buf = xfer->tx_buf; + sgt = &espi->tx_sgt; + + conf.dst_addr = espi->sspdr_phys; + conf.dst_addr_width = buswidth; + } + + ret = dmaengine_slave_config(chan, &conf); + if (ret) + return ERR_PTR(ret); + + /* + * We need to split the transfer into PAGE_SIZE'd chunks. This is + * because we are using @espi->zeropage to provide a zero RX buffer + * for the TX transfers and we have only allocated one page for that. + * + * For performance reasons we allocate a new sg_table only when + * needed. Otherwise we will re-use the current one. Eventually the + * last sg_table is released in ep93xx_spi_release_dma(). + */ + + nents = DIV_ROUND_UP(len, PAGE_SIZE); + if (nents != sgt->nents) { + sg_free_table(sgt); + + ret = sg_alloc_table(sgt, nents, GFP_KERNEL); + if (ret) + return ERR_PTR(ret); + } + + pbuf = buf; + for_each_sg(sgt->sgl, sg, sgt->nents, i) { + size_t bytes = min_t(size_t, len, PAGE_SIZE); + + if (buf) { + sg_set_page(sg, virt_to_page(pbuf), bytes, + offset_in_page(pbuf)); + } else { + sg_set_page(sg, virt_to_page(espi->zeropage), + bytes, 0); + } + + pbuf += bytes; + len -= bytes; + } + + if (WARN_ON(len)) { + dev_warn(&host->dev, "len = %zu expected 0!\n", len); + return ERR_PTR(-EINVAL); + } + + nents = dma_map_sg(chan->device->dev, sgt->sgl, sgt->nents, dir); + if (!nents) + return ERR_PTR(-ENOMEM); + + txd = dmaengine_prep_slave_sg(chan, sgt->sgl, nents, conf.direction, + DMA_CTRL_ACK); + if (!txd) { + dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir); + return ERR_PTR(-ENOMEM); + } + return txd; +} + +/** + * ep93xx_spi_dma_finish() - finishes with a DMA transfer + * @host: SPI host + * @dir: DMA transfer direction + * + * Function finishes with the DMA transfer. After this, the DMA buffer is + * unmapped. + */ +static void ep93xx_spi_dma_finish(struct spi_controller *host, + enum dma_data_direction dir) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + struct dma_chan *chan; + struct sg_table *sgt; + + if (dir == DMA_FROM_DEVICE) { + chan = espi->dma_rx; + sgt = &espi->rx_sgt; + } else { + chan = espi->dma_tx; + sgt = &espi->tx_sgt; + } + + dma_unmap_sg(chan->device->dev, sgt->sgl, sgt->nents, dir); +} + +static void ep93xx_spi_dma_callback(void *callback_param) +{ + struct spi_controller *host = callback_param; + + ep93xx_spi_dma_finish(host, DMA_TO_DEVICE); + ep93xx_spi_dma_finish(host, DMA_FROM_DEVICE); + + spi_finalize_current_transfer(host); +} + +static int ep93xx_spi_dma_transfer(struct spi_controller *host) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + struct dma_async_tx_descriptor *rxd, *txd; + + rxd = ep93xx_spi_dma_prepare(host, DMA_FROM_DEVICE); + if (IS_ERR(rxd)) { + dev_err(&host->dev, "DMA RX failed: %ld\n", PTR_ERR(rxd)); + return PTR_ERR(rxd); + } + + txd = ep93xx_spi_dma_prepare(host, DMA_TO_DEVICE); + if (IS_ERR(txd)) { + ep93xx_spi_dma_finish(host, DMA_FROM_DEVICE); + dev_err(&host->dev, "DMA TX failed: %ld\n", PTR_ERR(txd)); + return PTR_ERR(txd); + } + + /* We are ready when RX is done */ + rxd->callback = ep93xx_spi_dma_callback; + rxd->callback_param = host; + + /* Now submit both descriptors and start DMA */ + dmaengine_submit(rxd); + dmaengine_submit(txd); + + dma_async_issue_pending(espi->dma_rx); + dma_async_issue_pending(espi->dma_tx); + + /* signal that we need to wait for completion */ + return 1; +} + +static irqreturn_t ep93xx_spi_interrupt(int irq, void *dev_id) +{ + struct spi_controller *host = dev_id; + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + u32 val; + + /* + * If we got ROR (receive overrun) interrupt we know that something is + * wrong. Just abort the message. + */ + if (readl(espi->mmio + SSPIIR) & SSPIIR_RORIS) { + /* clear the overrun interrupt */ + writel(0, espi->mmio + SSPICR); + dev_warn(&host->dev, + "receive overrun, aborting the message\n"); + host->cur_msg->status = -EIO; + } else { + /* + * Interrupt is either RX (RIS) or TX (TIS). For both cases we + * simply execute next data transfer. + */ + if (ep93xx_spi_read_write(host)) { + /* + * In normal case, there still is some processing left + * for current transfer. Let's wait for the next + * interrupt then. + */ + return IRQ_HANDLED; + } + } + + /* + * Current transfer is finished, either with error or with success. In + * any case we disable interrupts and notify the worker to handle + * any post-processing of the message. + */ + val = readl(espi->mmio + SSPCR1); + val &= ~(SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE); + writel(val, espi->mmio + SSPCR1); + + spi_finalize_current_transfer(host); + + return IRQ_HANDLED; +} + +static int ep93xx_spi_transfer_one(struct spi_controller *host, + struct spi_device *spi, + struct spi_transfer *xfer) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + u32 val; + int ret; + + ret = ep93xx_spi_chip_setup(host, spi, xfer); + if (ret) { + dev_err(&host->dev, "failed to setup chip for transfer\n"); + return ret; + } + + host->cur_msg->state = xfer; + espi->rx = 0; + espi->tx = 0; + + /* + * There is no point of setting up DMA for the transfers which will + * fit into the FIFO and can be transferred with a single interrupt. + * So in these cases we will be using PIO and don't bother for DMA. + */ + if (espi->dma_rx && xfer->len > SPI_FIFO_SIZE) + return ep93xx_spi_dma_transfer(host); + + /* Using PIO so prime the TX FIFO and enable interrupts */ + ep93xx_spi_read_write(host); + + val = readl(espi->mmio + SSPCR1); + val |= (SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE); + writel(val, espi->mmio + SSPCR1); + + /* signal that we need to wait for completion */ + return 1; +} + +static int ep93xx_spi_prepare_message(struct spi_controller *host, + struct spi_message *msg) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + unsigned long timeout; + + /* + * Just to be sure: flush any data from RX FIFO. + */ + timeout = jiffies + msecs_to_jiffies(SPI_TIMEOUT); + while (readl(espi->mmio + SSPSR) & SSPSR_RNE) { + if (time_after(jiffies, timeout)) { + dev_warn(&host->dev, + "timeout while flushing RX FIFO\n"); + return -ETIMEDOUT; + } + readl(espi->mmio + SSPDR); + } + + /* + * We explicitly handle FIFO level. This way we don't have to check TX + * FIFO status using %SSPSR_TNF bit which may cause RX FIFO overruns. + */ + espi->fifo_level = 0; + + return 0; +} + +static int ep93xx_spi_prepare_hardware(struct spi_controller *host) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + u32 val; + int ret; + + ret = clk_prepare_enable(espi->clk); + if (ret) + return ret; + + val = readl(espi->mmio + SSPCR1); + val |= SSPCR1_SSE; + writel(val, espi->mmio + SSPCR1); + + return 0; +} + +static int ep93xx_spi_unprepare_hardware(struct spi_controller *host) +{ + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + u32 val; + + val = readl(espi->mmio + SSPCR1); + val &= ~SSPCR1_SSE; + writel(val, espi->mmio + SSPCR1); + + clk_disable_unprepare(espi->clk); + + return 0; +} + +static bool ep93xx_spi_dma_filter(struct dma_chan *chan, void *filter_param) +{ + if (ep93xx_dma_chan_is_m2p(chan)) + return false; + + chan->private = filter_param; + return true; +} + +static int ep93xx_spi_setup_dma(struct ep93xx_spi *espi) +{ + dma_cap_mask_t mask; + int ret; + + espi->zeropage = (void *)get_zeroed_page(GFP_KERNEL); + if (!espi->zeropage) + return -ENOMEM; + + dma_cap_zero(mask); + dma_cap_set(DMA_SLAVE, mask); + + espi->dma_rx_data.port = EP93XX_DMA_SSP; + espi->dma_rx_data.direction = DMA_DEV_TO_MEM; + espi->dma_rx_data.name = "ep93xx-spi-rx"; + + espi->dma_rx = dma_request_channel(mask, ep93xx_spi_dma_filter, + &espi->dma_rx_data); + if (!espi->dma_rx) { + ret = -ENODEV; + goto fail_free_page; + } + + espi->dma_tx_data.port = EP93XX_DMA_SSP; + espi->dma_tx_data.direction = DMA_MEM_TO_DEV; + espi->dma_tx_data.name = "ep93xx-spi-tx"; + + espi->dma_tx = dma_request_channel(mask, ep93xx_spi_dma_filter, + &espi->dma_tx_data); + if (!espi->dma_tx) { + ret = -ENODEV; + goto fail_release_rx; + } + + return 0; + +fail_release_rx: + dma_release_channel(espi->dma_rx); + espi->dma_rx = NULL; +fail_free_page: + free_page((unsigned long)espi->zeropage); + + return ret; +} + +static void ep93xx_spi_release_dma(struct ep93xx_spi *espi) +{ + if (espi->dma_rx) { + dma_release_channel(espi->dma_rx); + sg_free_table(&espi->rx_sgt); + } + if (espi->dma_tx) { + dma_release_channel(espi->dma_tx); + sg_free_table(&espi->tx_sgt); + } + + if (espi->zeropage) + free_page((unsigned long)espi->zeropage); +} + +static int ep93xx_spi_probe(struct platform_device *pdev) +{ + struct spi_controller *host; + struct ep93xx_spi_info *info; + struct ep93xx_spi *espi; + struct resource *res; + int irq; + int error; + + info = dev_get_platdata(&pdev->dev); + if (!info) { + dev_err(&pdev->dev, "missing platform data\n"); + return -EINVAL; + } + + irq = platform_get_irq(pdev, 0); + if (irq < 0) + return irq; + + host = spi_alloc_host(&pdev->dev, sizeof(*espi)); + if (!host) + return -ENOMEM; + + host->use_gpio_descriptors = true; + host->prepare_transfer_hardware = ep93xx_spi_prepare_hardware; + host->unprepare_transfer_hardware = ep93xx_spi_unprepare_hardware; + host->prepare_message = ep93xx_spi_prepare_message; + host->transfer_one = ep93xx_spi_transfer_one; + host->bus_num = pdev->id; + host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH; + host->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 16); + /* + * The SPI core will count the number of GPIO descriptors to figure + * out the number of chip selects available on the platform. + */ + host->num_chipselect = 0; + + platform_set_drvdata(pdev, host); + + espi = spi_controller_get_devdata(host); + + espi->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(espi->clk)) { + dev_err(&pdev->dev, "unable to get spi clock\n"); + error = PTR_ERR(espi->clk); + goto fail_release_host; + } + + /* + * Calculate maximum and minimum supported clock rates + * for the controller. + */ + host->max_speed_hz = clk_get_rate(espi->clk) / 2; + host->min_speed_hz = clk_get_rate(espi->clk) / (254 * 256); + + espi->mmio = devm_platform_get_and_ioremap_resource(pdev, 0, &res); + if (IS_ERR(espi->mmio)) { + error = PTR_ERR(espi->mmio); + goto fail_release_host; + } + espi->sspdr_phys = res->start + SSPDR; + + error = devm_request_irq(&pdev->dev, irq, ep93xx_spi_interrupt, + 0, "ep93xx-spi", host); + if (error) { + dev_err(&pdev->dev, "failed to request irq\n"); + goto fail_release_host; + } + + if (info->use_dma && ep93xx_spi_setup_dma(espi)) + dev_warn(&pdev->dev, "DMA setup failed. Falling back to PIO\n"); + + /* make sure that the hardware is disabled */ + writel(0, espi->mmio + SSPCR1); + + error = devm_spi_register_controller(&pdev->dev, host); + if (error) { + dev_err(&pdev->dev, "failed to register SPI host\n"); + goto fail_free_dma; + } + + dev_info(&pdev->dev, "EP93xx SPI Controller at 0x%08lx irq %d\n", + (unsigned long)res->start, irq); + + return 0; + +fail_free_dma: + ep93xx_spi_release_dma(espi); +fail_release_host: + spi_controller_put(host); + + return error; +} + +static void ep93xx_spi_remove(struct platform_device *pdev) +{ + struct spi_controller *host = platform_get_drvdata(pdev); + struct ep93xx_spi *espi = spi_controller_get_devdata(host); + + ep93xx_spi_release_dma(espi); +} + +static struct platform_driver ep93xx_spi_driver = { + .driver = { + .name = "ep93xx-spi", + }, + .probe = ep93xx_spi_probe, + .remove_new = ep93xx_spi_remove, +}; +module_platform_driver(ep93xx_spi_driver); + +MODULE_DESCRIPTION("EP93xx SPI Controller driver"); +MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:ep93xx-spi"); |