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Diffstat (limited to 'drivers/spi/spi-ep93xx.c')
| -rw-r--r-- | drivers/spi/spi-ep93xx.c | 1217 |
1 files changed, 1217 insertions, 0 deletions
diff --git a/drivers/spi/spi-ep93xx.c b/drivers/spi/spi-ep93xx.c new file mode 100644 index 000000000000..1cf645479bfe --- /dev/null +++ b/drivers/spi/spi-ep93xx.c @@ -0,0 +1,1217 @@ +/* + * 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: + * http://www.cirrus.com/en/pubs/manual/EP93xx_Users_Guide_UM1.pdf + * + * 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. + */ + +#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/platform_device.h> +#include <linux/workqueue.h> +#include <linux/sched.h> +#include <linux/scatterlist.h> +#include <linux/spi/spi.h> + +#include <mach/dma.h> +#include <mach/ep93xx_spi.h> + +#define SSPCR0 0x0000 +#define SSPCR0_MODE_SHIFT 6 +#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 + * @lock: spinlock that protects concurrent accesses to fields @running, + * @current_msg and @msg_queue + * @pdev: pointer to platform device + * @clk: clock for the controller + * @regs_base: pointer to ioremap()'d registers + * @sspdr_phys: physical address of the SSPDR register + * @irq: IRQ number used by the driver + * @min_rate: minimum clock rate (in Hz) supported by the controller + * @max_rate: maximum clock rate (in Hz) supported by the controller + * @running: is the queue running + * @wq: workqueue used by the driver + * @msg_work: work that is queued for the driver + * @wait: wait here until given transfer is completed + * @msg_queue: queue for the messages + * @current_msg: message that is currently processed (or %NULL if none) + * @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 + * + * This structure holds EP93xx SPI controller specific information. When + * @running is %true, driver accepts transfer requests from protocol drivers. + * @current_msg is used to hold pointer to the message that is currently + * processed. If @current_msg is %NULL, it means that no processing is going + * on. + * + * Most of the fields are only written once and they can be accessed without + * taking the @lock. Fields that are accessed concurrently are: @current_msg, + * @running, and @msg_queue. + */ +struct ep93xx_spi { + spinlock_t lock; + const struct platform_device *pdev; + struct clk *clk; + void __iomem *regs_base; + unsigned long sspdr_phys; + int irq; + unsigned long min_rate; + unsigned long max_rate; + bool running; + struct workqueue_struct *wq; + struct work_struct msg_work; + struct completion wait; + struct list_head msg_queue; + struct spi_message *current_msg; + 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; +}; + +/** + * struct ep93xx_spi_chip - SPI device hardware settings + * @spi: back pointer to the SPI device + * @rate: max rate in hz this chip supports + * @div_cpsr: cpsr (pre-scaler) divider + * @div_scr: scr divider + * @dss: bits per word (4 - 16 bits) + * @ops: private chip operations + * + * This structure is used to store hardware register specific settings for each + * SPI device. Settings are written to hardware by function + * ep93xx_spi_chip_setup(). + */ +struct ep93xx_spi_chip { + const struct spi_device *spi; + unsigned long rate; + u8 div_cpsr; + u8 div_scr; + u8 dss; + struct ep93xx_spi_chip_ops *ops; +}; + +/* converts bits per word to CR0.DSS value */ +#define bits_per_word_to_dss(bpw) ((bpw) - 1) + +static inline void +ep93xx_spi_write_u8(const struct ep93xx_spi *espi, u16 reg, u8 value) +{ + __raw_writeb(value, espi->regs_base + reg); +} + +static inline u8 +ep93xx_spi_read_u8(const struct ep93xx_spi *spi, u16 reg) +{ + return __raw_readb(spi->regs_base + reg); +} + +static inline void +ep93xx_spi_write_u16(const struct ep93xx_spi *espi, u16 reg, u16 value) +{ + __raw_writew(value, espi->regs_base + reg); +} + +static inline u16 +ep93xx_spi_read_u16(const struct ep93xx_spi *spi, u16 reg) +{ + return __raw_readw(spi->regs_base + reg); +} + +static int ep93xx_spi_enable(const struct ep93xx_spi *espi) +{ + u8 regval; + int err; + + err = clk_enable(espi->clk); + if (err) + return err; + + regval = ep93xx_spi_read_u8(espi, SSPCR1); + regval |= SSPCR1_SSE; + ep93xx_spi_write_u8(espi, SSPCR1, regval); + + return 0; +} + +static void ep93xx_spi_disable(const struct ep93xx_spi *espi) +{ + u8 regval; + + regval = ep93xx_spi_read_u8(espi, SSPCR1); + regval &= ~SSPCR1_SSE; + ep93xx_spi_write_u8(espi, SSPCR1, regval); + + clk_disable(espi->clk); +} + +static void ep93xx_spi_enable_interrupts(const struct ep93xx_spi *espi) +{ + u8 regval; + + regval = ep93xx_spi_read_u8(espi, SSPCR1); + regval |= (SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE); + ep93xx_spi_write_u8(espi, SSPCR1, regval); +} + +static void ep93xx_spi_disable_interrupts(const struct ep93xx_spi *espi) +{ + u8 regval; + + regval = ep93xx_spi_read_u8(espi, SSPCR1); + regval &= ~(SSPCR1_RORIE | SSPCR1_TIE | SSPCR1_RIE); + ep93xx_spi_write_u8(espi, SSPCR1, regval); +} + +/** + * ep93xx_spi_calc_divisors() - calculates SPI clock divisors + * @espi: ep93xx SPI controller struct + * @chip: divisors are calculated for this chip + * @rate: desired SPI output clock rate + * + * Function calculates cpsr (clock pre-scaler) and scr divisors based on + * given @rate and places them to @chip->div_cpsr and @chip->div_scr. If, + * for some reason, divisors cannot be calculated nothing is stored and + * %-EINVAL is returned. + */ +static int ep93xx_spi_calc_divisors(const struct ep93xx_spi *espi, + struct ep93xx_spi_chip *chip, + unsigned long rate) +{ + 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. Note that minimum value is already checked in + * ep93xx_spi_transfer(). + */ + rate = clamp(rate, espi->min_rate, espi->max_rate); + + /* + * 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) { + chip->div_scr = (u8)scr; + chip->div_cpsr = (u8)cpsr; + return 0; + } + } + } + + return -EINVAL; +} + +static void ep93xx_spi_cs_control(struct spi_device *spi, bool control) +{ + struct ep93xx_spi_chip *chip = spi_get_ctldata(spi); + int value = (spi->mode & SPI_CS_HIGH) ? control : !control; + + if (chip->ops && chip->ops->cs_control) + chip->ops->cs_control(spi, value); +} + +/** + * ep93xx_spi_setup() - setup an SPI device + * @spi: SPI device to setup + * + * This function sets up SPI device mode, speed etc. Can be called multiple + * times for a single device. Returns %0 in case of success, negative error in + * case of failure. When this function returns success, the device is + * deselected. + */ +static int ep93xx_spi_setup(struct spi_device *spi) +{ + struct ep93xx_spi *espi = spi_master_get_devdata(spi->master); + struct ep93xx_spi_chip *chip; + + if (spi->bits_per_word < 4 || spi->bits_per_word > 16) { + dev_err(&espi->pdev->dev, "invalid bits per word %d\n", + spi->bits_per_word); + return -EINVAL; + } + + chip = spi_get_ctldata(spi); + if (!chip) { + dev_dbg(&espi->pdev->dev, "initial setup for %s\n", + spi->modalias); + + chip = kzalloc(sizeof(*chip), GFP_KERNEL); + if (!chip) + return -ENOMEM; + + chip->spi = spi; + chip->ops = spi->controller_data; + + if (chip->ops && chip->ops->setup) { + int ret = chip->ops->setup(spi); + if (ret) { + kfree(chip); + return ret; + } + } + + spi_set_ctldata(spi, chip); + } + + if (spi->max_speed_hz != chip->rate) { + int err; + + err = ep93xx_spi_calc_divisors(espi, chip, spi->max_speed_hz); + if (err != 0) { + spi_set_ctldata(spi, NULL); + kfree(chip); + return err; + } + chip->rate = spi->max_speed_hz; + } + + chip->dss = bits_per_word_to_dss(spi->bits_per_word); + + ep93xx_spi_cs_control(spi, false); + return 0; +} + +/** + * ep93xx_spi_transfer() - queue message to be transferred + * @spi: target SPI device + * @msg: message to be transferred + * + * This function is called by SPI device drivers when they are going to transfer + * a new message. It simply puts the message in the queue and schedules + * workqueue to perform the actual transfer later on. + * + * Returns %0 on success and negative error in case of failure. + */ +static int ep93xx_spi_transfer(struct spi_device *spi, struct spi_message *msg) +{ + struct ep93xx_spi *espi = spi_master_get_devdata(spi->master); + struct spi_transfer *t; + unsigned long flags; + + if (!msg || !msg->complete) + return -EINVAL; + + /* first validate each transfer */ + list_for_each_entry(t, &msg->transfers, transfer_list) { + if (t->bits_per_word) { + if (t->bits_per_word < 4 || t->bits_per_word > 16) + return -EINVAL; + } + if (t->speed_hz && t->speed_hz < espi->min_rate) + return -EINVAL; + } + + /* + * Now that we own the message, let's initialize it so that it is + * suitable for us. We use @msg->status to signal whether there was + * error in transfer and @msg->state is used to hold pointer to the + * current transfer (or %NULL if no active current transfer). + */ + msg->state = NULL; + msg->status = 0; + msg->actual_length = 0; + + spin_lock_irqsave(&espi->lock, flags); + if (!espi->running) { + spin_unlock_irqrestore(&espi->lock, flags); + return -ESHUTDOWN; + } + list_add_tail(&msg->queue, &espi->msg_queue); + queue_work(espi->wq, &espi->msg_work); + spin_unlock_irqrestore(&espi->lock, flags); + + return 0; +} + +/** + * ep93xx_spi_cleanup() - cleans up master controller specific state + * @spi: SPI device to cleanup + * + * This function releases master controller specific state for given @spi + * device. + */ +static void ep93xx_spi_cleanup(struct spi_device *spi) +{ + struct ep93xx_spi_chip *chip; + + chip = spi_get_ctldata(spi); + if (chip) { + if (chip->ops && chip->ops->cleanup) + chip->ops->cleanup(spi); + spi_set_ctldata(spi, NULL); + kfree(chip); + } +} + +/** + * ep93xx_spi_chip_setup() - configures hardware according to given @chip + * @espi: ep93xx SPI controller struct + * @chip: chip specific settings + * + * This function sets up the actual hardware registers with settings given in + * @chip. Note that no validation is done so make sure that callers validate + * settings before calling this. + */ +static void ep93xx_spi_chip_setup(const struct ep93xx_spi *espi, + const struct ep93xx_spi_chip *chip) +{ + u16 cr0; + + cr0 = chip->div_scr << SSPCR0_SCR_SHIFT; + cr0 |= (chip->spi->mode & (SPI_CPHA|SPI_CPOL)) << SSPCR0_MODE_SHIFT; + cr0 |= chip->dss; + + dev_dbg(&espi->pdev->dev, "setup: mode %d, cpsr %d, scr %d, dss %d\n", + chip->spi->mode, chip->div_cpsr, chip->div_scr, chip->dss); + dev_dbg(&espi->pdev->dev, "setup: cr0 %#x", cr0); + + ep93xx_spi_write_u8(espi, SSPCPSR, chip->div_cpsr); + ep93xx_spi_write_u16(espi, SSPCR0, cr0); +} + +static inline int bits_per_word(const struct ep93xx_spi *espi) +{ + struct spi_message *msg = espi->current_msg; + struct spi_transfer *t = msg->state; + + return t->bits_per_word ? t->bits_per_word : msg->spi->bits_per_word; +} + +static void ep93xx_do_write(struct ep93xx_spi *espi, struct spi_transfer *t) +{ + if (bits_per_word(espi) > 8) { + u16 tx_val = 0; + + if (t->tx_buf) + tx_val = ((u16 *)t->tx_buf)[espi->tx]; + ep93xx_spi_write_u16(espi, SSPDR, tx_val); + espi->tx += sizeof(tx_val); + } else { + u8 tx_val = 0; + + if (t->tx_buf) + tx_val = ((u8 *)t->tx_buf)[espi->tx]; + ep93xx_spi_write_u8(espi, SSPDR, tx_val); + espi->tx += sizeof(tx_val); + } +} + +static void ep93xx_do_read(struct ep93xx_spi *espi, struct spi_transfer *t) +{ + if (bits_per_word(espi) > 8) { + u16 rx_val; + + rx_val = ep93xx_spi_read_u16(espi, SSPDR); + if (t->rx_buf) + ((u16 *)t->rx_buf)[espi->rx] = rx_val; + espi->rx += sizeof(rx_val); + } else { + u8 rx_val; + + rx_val = ep93xx_spi_read_u8(espi, SSPDR); + if (t->rx_buf) + ((u8 *)t->rx_buf)[espi->rx] = rx_val; + espi->rx += sizeof(rx_val); + } +} + +/** + * ep93xx_spi_read_write() - perform next RX/TX transfer + * @espi: ep93xx SPI controller struct + * + * 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 ep93xx_spi *espi) +{ + struct spi_message *msg = espi->current_msg; + struct spi_transfer *t = msg->state; + + /* read as long as RX FIFO has frames in it */ + while ((ep93xx_spi_read_u8(espi, SSPSR) & SSPSR_RNE)) { + ep93xx_do_read(espi, t); + espi->fifo_level--; + } + + /* write as long as TX FIFO has room */ + while (espi->fifo_level < SPI_FIFO_SIZE && espi->tx < t->len) { + ep93xx_do_write(espi, t); + espi->fifo_level++; + } + + if (espi->rx == t->len) + return 0; + + return -EINPROGRESS; +} + +static void ep93xx_spi_pio_transfer(struct ep93xx_spi *espi) +{ + /* + * Now everything is set up for the current transfer. We prime the TX + * FIFO, enable interrupts, and wait for the transfer to complete. + */ + if (ep93xx_spi_read_write(espi)) { + ep93xx_spi_enable_interrupts(espi); + wait_for_completion(&espi->wait); + } +} + +/** + * ep93xx_spi_dma_prepare() - prepares a DMA transfer + * @espi: ep93xx SPI controller struct + * @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 ep93xx_spi *espi, enum dma_data_direction dir) +{ + struct spi_transfer *t = espi->current_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 = t->len; + int i, ret, nents; + + if (bits_per_word(espi) > 8) + buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES; + else + buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE; + + memset(&conf, 0, sizeof(conf)); + conf.direction = dir; + + if (dir == DMA_FROM_DEVICE) { + chan = espi->dma_rx; + buf = t->rx_buf; + sgt = &espi->rx_sgt; + + conf.src_addr = espi->sspdr_phys; + conf.src_addr_width = buswidth; + } else { + chan = espi->dma_tx; + buf = t->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(&espi->pdev->dev, "len = %d expected 0!", len); + return ERR_PTR(-EINVAL); + } + + nents = dma_map_sg(chan->device->dev, sgt->sgl, sgt->nents, dir); + if (!nents) + return ERR_PTR(-ENOMEM); + + txd = chan->device->device_prep_slave_sg(chan, sgt->sgl, nents, + dir, 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 + * @espi: ep93xx SPI controller struct + * @dir: DMA transfer direction + * + * Function finishes with the DMA transfer. After this, the DMA buffer is + * unmapped. + */ +static void ep93xx_spi_dma_finish(struct ep93xx_spi *espi, + enum dma_data_direction dir) +{ + 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) +{ + complete(callback_param); +} + +static void ep93xx_spi_dma_transfer(struct ep93xx_spi *espi) +{ + struct spi_message *msg = espi->current_msg; + struct dma_async_tx_descriptor *rxd, *txd; + + rxd = ep93xx_spi_dma_prepare(espi, DMA_FROM_DEVICE); + if (IS_ERR(rxd)) { + dev_err(&espi->pdev->dev, "DMA RX failed: %ld\n", PTR_ERR(rxd)); + msg->status = PTR_ERR(rxd); + return; + } + + txd = ep93xx_spi_dma_prepare(espi, DMA_TO_DEVICE); + if (IS_ERR(txd)) { + ep93xx_spi_dma_finish(espi, DMA_FROM_DEVICE); + dev_err(&espi->pdev->dev, "DMA TX failed: %ld\n", PTR_ERR(rxd)); + msg->status = PTR_ERR(txd); + return; + } + + /* We are ready when RX is done */ + rxd->callback = ep93xx_spi_dma_callback; + rxd->callback_param = &espi->wait; + + /* Now submit both descriptors and wait while they finish */ + dmaengine_submit(rxd); + dmaengine_submit(txd); + + dma_async_issue_pending(espi->dma_rx); + dma_async_issue_pending(espi->dma_tx); + + wait_for_completion(&espi->wait); + + ep93xx_spi_dma_finish(espi, DMA_TO_DEVICE); + ep93xx_spi_dma_finish(espi, DMA_FROM_DEVICE); +} + +/** + * ep93xx_spi_process_transfer() - processes one SPI transfer + * @espi: ep93xx SPI controller struct + * @msg: current message + * @t: transfer to process + * + * This function processes one SPI transfer given in @t. Function waits until + * transfer is complete (may sleep) and updates @msg->status based on whether + * transfer was successfully processed or not. + */ +static void ep93xx_spi_process_transfer(struct ep93xx_spi *espi, + struct spi_message *msg, + struct spi_transfer *t) +{ + struct ep93xx_spi_chip *chip = spi_get_ctldata(msg->spi); + + msg->state = t; + + /* + * Handle any transfer specific settings if needed. We use + * temporary chip settings here and restore original later when + * the transfer is finished. + */ + if (t->speed_hz || t->bits_per_word) { + struct ep93xx_spi_chip tmp_chip = *chip; + + if (t->speed_hz) { + int err; + + err = ep93xx_spi_calc_divisors(espi, &tmp_chip, + t->speed_hz); + if (err) { + dev_err(&espi->pdev->dev, + "failed to adjust speed\n"); + msg->status = err; + return; + } + } + + if (t->bits_per_word) + tmp_chip.dss = bits_per_word_to_dss(t->bits_per_word); + + /* + * Set up temporary new hw settings for this transfer. + */ + ep93xx_spi_chip_setup(espi, &tmp_chip); + } + + 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 && t->len > SPI_FIFO_SIZE) + ep93xx_spi_dma_transfer(espi); + else + ep93xx_spi_pio_transfer(espi); + + /* + * In case of error during transmit, we bail out from processing + * the message. + */ + if (msg->status) + return; + + msg->actual_length += t->len; + + /* + * After this transfer is finished, perform any possible + * post-transfer actions requested by the protocol driver. + */ + if (t->delay_usecs) { + set_current_state(TASK_UNINTERRUPTIBLE); + schedule_timeout(usecs_to_jiffies(t->delay_usecs)); + } + if (t->cs_change) { + if (!list_is_last(&t->transfer_list, &msg->transfers)) { + /* + * In case protocol driver is asking us to drop the + * chipselect briefly, we let the scheduler to handle + * any "delay" here. + */ + ep93xx_spi_cs_control(msg->spi, false); + cond_resched(); + ep93xx_spi_cs_control(msg->spi, true); + } + } + + if (t->speed_hz || t->bits_per_word) + ep93xx_spi_chip_setup(espi, chip); +} + +/* + * ep93xx_spi_process_message() - process one SPI message + * @espi: ep93xx SPI controller struct + * @msg: message to process + * + * This function processes a single SPI message. We go through all transfers in + * the message and pass them to ep93xx_spi_process_transfer(). Chipselect is + * asserted during the whole message (unless per transfer cs_change is set). + * + * @msg->status contains %0 in case of success or negative error code in case of + * failure. + */ +static void ep93xx_spi_process_message(struct ep93xx_spi *espi, + struct spi_message *msg) +{ + unsigned long timeout; + struct spi_transfer *t; + int err; + + /* + * Enable the SPI controller and its clock. + */ + err = ep93xx_spi_enable(espi); + if (err) { + dev_err(&espi->pdev->dev, "failed to enable SPI controller\n"); + msg->status = err; + return; + } + + /* + * Just to be sure: flush any data from RX FIFO. + */ + timeout = jiffies + msecs_to_jiffies(SPI_TIMEOUT); + while (ep93xx_spi_read_u16(espi, SSPSR) & SSPSR_RNE) { + if (time_after(jiffies, timeout)) { + dev_warn(&espi->pdev->dev, + "timeout while flushing RX FIFO\n"); + msg->status = -ETIMEDOUT; + return; + } + ep93xx_spi_read_u16(espi, 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; + + /* + * Update SPI controller registers according to spi device and assert + * the chipselect. + */ + ep93xx_spi_chip_setup(espi, spi_get_ctldata(msg->spi)); + ep93xx_spi_cs_control(msg->spi, true); + + list_for_each_entry(t, &msg->transfers, transfer_list) { + ep93xx_spi_process_transfer(espi, msg, t); + if (msg->status) + break; + } + + /* + * Now the whole message is transferred (or failed for some reason). We + * deselect the device and disable the SPI controller. + */ + ep93xx_spi_cs_control(msg->spi, false); + ep93xx_spi_disable(espi); +} + +#define work_to_espi(work) (container_of((work), struct ep93xx_spi, msg_work)) + +/** + * ep93xx_spi_work() - EP93xx SPI workqueue worker function + * @work: work struct + * + * Workqueue worker function. This function is called when there are new + * SPI messages to be processed. Message is taken out from the queue and then + * passed to ep93xx_spi_process_message(). + * + * After message is transferred, protocol driver is notified by calling + * @msg->complete(). In case of error, @msg->status is set to negative error + * number, otherwise it contains zero (and @msg->actual_length is updated). + */ +static void ep93xx_spi_work(struct work_struct *work) +{ + struct ep93xx_spi *espi = work_to_espi(work); + struct spi_message *msg; + + spin_lock_irq(&espi->lock); + if (!espi->running || espi->current_msg || + list_empty(&espi->msg_queue)) { + spin_unlock_irq(&espi->lock); + return; + } + msg = list_first_entry(&espi->msg_queue, struct spi_message, queue); + list_del_init(&msg->queue); + espi->current_msg = msg; + spin_unlock_irq(&espi->lock); + + ep93xx_spi_process_message(espi, msg); + + /* + * Update the current message and re-schedule ourselves if there are + * more messages in the queue. + */ + spin_lock_irq(&espi->lock); + espi->current_msg = NULL; + if (espi->running && !list_empty(&espi->msg_queue)) + queue_work(espi->wq, &espi->msg_work); + spin_unlock_irq(&espi->lock); + + /* notify the protocol driver that we are done with this message */ + msg->complete(msg->context); +} + +static irqreturn_t ep93xx_spi_interrupt(int irq, void *dev_id) +{ + struct ep93xx_spi *espi = dev_id; + u8 irq_status = ep93xx_spi_read_u8(espi, SSPIIR); + + /* + * If we got ROR (receive overrun) interrupt we know that something is + * wrong. Just abort the message. + */ + if (unlikely(irq_status & SSPIIR_RORIS)) { + /* clear the overrun interrupt */ + ep93xx_spi_write_u8(espi, SSPICR, 0); + dev_warn(&espi->pdev->dev, + "receive overrun, aborting the message\n"); + espi->current_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(espi)) { + /* + * 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. + */ + ep93xx_spi_disable_interrupts(espi); + complete(&espi->wait); + return IRQ_HANDLED; +} + +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_FROM_DEVICE; + 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_TO_DEVICE; + 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 __init ep93xx_spi_probe(struct platform_device *pdev) +{ + struct spi_master *master; + struct ep93xx_spi_info *info; + struct ep93xx_spi *espi; + struct resource *res; + int error; + + info = pdev->dev.platform_data; + + master = spi_alloc_master(&pdev->dev, sizeof(*espi)); + if (!master) { + dev_err(&pdev->dev, "failed to allocate spi master\n"); + return -ENOMEM; + } + + master->setup = ep93xx_spi_setup; + master->transfer = ep93xx_spi_transfer; + master->cleanup = ep93xx_spi_cleanup; + master->bus_num = pdev->id; + master->num_chipselect = info->num_chipselect; + master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH; + + platform_set_drvdata(pdev, master); + + espi = spi_master_get_devdata(master); + + espi->clk = 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_master; + } + + spin_lock_init(&espi->lock); + init_completion(&espi->wait); + + /* + * Calculate maximum and minimum supported clock rates + * for the controller. + */ + espi->max_rate = clk_get_rate(espi->clk) / 2; + espi->min_rate = clk_get_rate(espi->clk) / (254 * 256); + espi->pdev = pdev; + + espi->irq = platform_get_irq(pdev, 0); + if (espi->irq < 0) { + error = -EBUSY; + dev_err(&pdev->dev, "failed to get irq resources\n"); + goto fail_put_clock; + } + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) { + dev_err(&pdev->dev, "unable to get iomem resource\n"); + error = -ENODEV; + goto fail_put_clock; + } + + res = request_mem_region(res->start, resource_size(res), pdev->name); + if (!res) { + dev_err(&pdev->dev, "unable to request iomem resources\n"); + error = -EBUSY; + goto fail_put_clock; + } + + espi->sspdr_phys = res->start + SSPDR; + espi->regs_base = ioremap(res->start, resource_size(res)); + if (!espi->regs_base) { + dev_err(&pdev->dev, "failed to map resources\n"); + error = -ENODEV; + goto fail_free_mem; + } + + error = request_irq(espi->irq, ep93xx_spi_interrupt, 0, + "ep93xx-spi", espi); + if (error) { + dev_err(&pdev->dev, "failed to request irq\n"); + goto fail_unmap_regs; + } + + if (info->use_dma && ep93xx_spi_setup_dma(espi)) + dev_warn(&pdev->dev, "DMA setup failed. Falling back to PIO\n"); + + espi->wq = create_singlethread_workqueue("ep93xx_spid"); + if (!espi->wq) { + dev_err(&pdev->dev, "unable to create workqueue\n"); + goto fail_free_dma; + } + INIT_WORK(&espi->msg_work, ep93xx_spi_work); + INIT_LIST_HEAD(&espi->msg_queue); + espi->running = true; + + /* make sure that the hardware is disabled */ + ep93xx_spi_write_u8(espi, SSPCR1, 0); + + error = spi_register_master(master); + if (error) { + dev_err(&pdev->dev, "failed to register SPI master\n"); + goto fail_free_queue; + } + + dev_info(&pdev->dev, "EP93xx SPI Controller at 0x%08lx irq %d\n", + (unsigned long)res->start, espi->irq); + + return 0; + +fail_free_queue: + destroy_workqueue(espi->wq); +fail_free_dma: + ep93xx_spi_release_dma(espi); + free_irq(espi->irq, espi); +fail_unmap_regs: + iounmap(espi->regs_base); +fail_free_mem: + release_mem_region(res->start, resource_size(res)); +fail_put_clock: + clk_put(espi->clk); +fail_release_master: + spi_master_put(master); + platform_set_drvdata(pdev, NULL); + + return error; +} + +static int __exit ep93xx_spi_remove(struct platform_device *pdev) +{ + struct spi_master *master = platform_get_drvdata(pdev); + struct ep93xx_spi *espi = spi_master_get_devdata(master); + struct resource *res; + + spin_lock_irq(&espi->lock); + espi->running = false; + spin_unlock_irq(&espi->lock); + + destroy_workqueue(espi->wq); + + /* + * Complete remaining messages with %-ESHUTDOWN status. + */ + spin_lock_irq(&espi->lock); + while (!list_empty(&espi->msg_queue)) { + struct spi_message *msg; + + msg = list_first_entry(&espi->msg_queue, + struct spi_message, queue); + list_del_init(&msg->queue); + msg->status = -ESHUTDOWN; + spin_unlock_irq(&espi->lock); + msg->complete(msg->context); + spin_lock_irq(&espi->lock); + } + spin_unlock_irq(&espi->lock); + + ep93xx_spi_release_dma(espi); + free_irq(espi->irq, espi); + iounmap(espi->regs_base); + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + release_mem_region(res->start, resource_size(res)); + clk_put(espi->clk); + platform_set_drvdata(pdev, NULL); + + spi_unregister_master(master); + return 0; +} + +static struct platform_driver ep93xx_spi_driver = { + .driver = { + .name = "ep93xx-spi", + .owner = THIS_MODULE, + }, + .remove = __exit_p(ep93xx_spi_remove), +}; + +static int __init ep93xx_spi_init(void) +{ + return platform_driver_probe(&ep93xx_spi_driver, ep93xx_spi_probe); +} +module_init(ep93xx_spi_init); + +static void __exit ep93xx_spi_exit(void) +{ + platform_driver_unregister(&ep93xx_spi_driver); +} +module_exit(ep93xx_spi_exit); + +MODULE_DESCRIPTION("EP93xx SPI Controller driver"); +MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:ep93xx-spi"); |