diff options
Diffstat (limited to 'drivers/spi/spi-s3c24xx.c')
| -rw-r--r-- | drivers/spi/spi-s3c24xx.c | 596 |
1 files changed, 596 insertions, 0 deletions
diff --git a/drivers/spi/spi-s3c24xx.c b/drivers/spi/spi-s3c24xx.c new file mode 100644 index 000000000..ef25b5e93 --- /dev/null +++ b/drivers/spi/spi-s3c24xx.c @@ -0,0 +1,596 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2006 Ben Dooks + * Copyright 2006-2009 Simtec Electronics + * Ben Dooks <ben@simtec.co.uk> +*/ + +#include <linux/spinlock.h> +#include <linux/interrupt.h> +#include <linux/delay.h> +#include <linux/errno.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/slab.h> + +#include <linux/spi/spi.h> +#include <linux/spi/spi_bitbang.h> +#include <linux/spi/s3c24xx.h> +#include <linux/spi/s3c24xx-fiq.h> +#include <linux/module.h> + +#include <asm/fiq.h> + +#include "spi-s3c24xx-regs.h" + +/** + * struct s3c24xx_spi_devstate - per device data + * @hz: Last frequency calculated for @sppre field. + * @mode: Last mode setting for the @spcon field. + * @spcon: Value to write to the SPCON register. + * @sppre: Value to write to the SPPRE register. + */ +struct s3c24xx_spi_devstate { + unsigned int hz; + unsigned int mode; + u8 spcon; + u8 sppre; +}; + +enum spi_fiq_mode { + FIQ_MODE_NONE = 0, + FIQ_MODE_TX = 1, + FIQ_MODE_RX = 2, + FIQ_MODE_TXRX = 3, +}; + +struct s3c24xx_spi { + /* bitbang has to be first */ + struct spi_bitbang bitbang; + struct completion done; + + void __iomem *regs; + int irq; + int len; + int count; + + struct fiq_handler fiq_handler; + enum spi_fiq_mode fiq_mode; + unsigned char fiq_inuse; + unsigned char fiq_claimed; + + /* data buffers */ + const unsigned char *tx; + unsigned char *rx; + + struct clk *clk; + struct spi_master *master; + struct spi_device *curdev; + struct device *dev; + struct s3c2410_spi_info *pdata; +}; + +#define SPCON_DEFAULT (S3C2410_SPCON_MSTR | S3C2410_SPCON_SMOD_INT) +#define SPPIN_DEFAULT (S3C2410_SPPIN_KEEP) + +static inline struct s3c24xx_spi *to_hw(struct spi_device *sdev) +{ + return spi_master_get_devdata(sdev->master); +} + +static void s3c24xx_spi_chipsel(struct spi_device *spi, int value) +{ + struct s3c24xx_spi_devstate *cs = spi->controller_state; + struct s3c24xx_spi *hw = to_hw(spi); + + /* change the chipselect state and the state of the spi engine clock */ + + switch (value) { + case BITBANG_CS_INACTIVE: + writeb(cs->spcon, hw->regs + S3C2410_SPCON); + break; + + case BITBANG_CS_ACTIVE: + writeb(cs->spcon | S3C2410_SPCON_ENSCK, + hw->regs + S3C2410_SPCON); + break; + } +} + +static int s3c24xx_spi_update_state(struct spi_device *spi, + struct spi_transfer *t) +{ + struct s3c24xx_spi *hw = to_hw(spi); + struct s3c24xx_spi_devstate *cs = spi->controller_state; + unsigned int hz; + unsigned int div; + unsigned long clk; + + hz = t ? t->speed_hz : spi->max_speed_hz; + + if (!hz) + hz = spi->max_speed_hz; + + if (spi->mode != cs->mode) { + u8 spcon = SPCON_DEFAULT | S3C2410_SPCON_ENSCK; + + if (spi->mode & SPI_CPHA) + spcon |= S3C2410_SPCON_CPHA_FMTB; + + if (spi->mode & SPI_CPOL) + spcon |= S3C2410_SPCON_CPOL_HIGH; + + cs->mode = spi->mode; + cs->spcon = spcon; + } + + if (cs->hz != hz) { + clk = clk_get_rate(hw->clk); + div = DIV_ROUND_UP(clk, hz * 2) - 1; + + if (div > 255) + div = 255; + + dev_dbg(&spi->dev, "pre-scaler=%d (wanted %d, got %ld)\n", + div, hz, clk / (2 * (div + 1))); + + cs->hz = hz; + cs->sppre = div; + } + + return 0; +} + +static int s3c24xx_spi_setupxfer(struct spi_device *spi, + struct spi_transfer *t) +{ + struct s3c24xx_spi_devstate *cs = spi->controller_state; + struct s3c24xx_spi *hw = to_hw(spi); + int ret; + + ret = s3c24xx_spi_update_state(spi, t); + if (!ret) + writeb(cs->sppre, hw->regs + S3C2410_SPPRE); + + return ret; +} + +static int s3c24xx_spi_setup(struct spi_device *spi) +{ + struct s3c24xx_spi_devstate *cs = spi->controller_state; + struct s3c24xx_spi *hw = to_hw(spi); + int ret; + + /* allocate settings on the first call */ + if (!cs) { + cs = devm_kzalloc(&spi->dev, + sizeof(struct s3c24xx_spi_devstate), + GFP_KERNEL); + if (!cs) + return -ENOMEM; + + cs->spcon = SPCON_DEFAULT; + cs->hz = -1; + spi->controller_state = cs; + } + + /* initialise the state from the device */ + ret = s3c24xx_spi_update_state(spi, NULL); + if (ret) + return ret; + + mutex_lock(&hw->bitbang.lock); + if (!hw->bitbang.busy) { + hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE); + /* need to ndelay for 0.5 clocktick ? */ + } + mutex_unlock(&hw->bitbang.lock); + + return 0; +} + +static inline unsigned int hw_txbyte(struct s3c24xx_spi *hw, int count) +{ + return hw->tx ? hw->tx[count] : 0; +} + +#ifdef CONFIG_SPI_S3C24XX_FIQ +/* Support for FIQ based pseudo-DMA to improve the transfer speed. + * + * This code uses the assembly helper in spi_s3c24xx_spi.S which is + * used by the FIQ core to move data between main memory and the peripheral + * block. Since this is code running on the processor, there is no problem + * with cache coherency of the buffers, so we can use any buffer we like. + */ + +/** + * struct spi_fiq_code - FIQ code and header + * @length: The length of the code fragment, excluding this header. + * @ack_offset: The offset from @data to the word to place the IRQ ACK bit at. + * @data: The code itself to install as a FIQ handler. + */ +struct spi_fiq_code { + u32 length; + u32 ack_offset; + u8 data[]; +}; + +/** + * s3c24xx_spi_tryfiq - attempt to claim and setup FIQ for transfer + * @hw: The hardware state. + * + * Claim the FIQ handler (only one can be active at any one time) and + * then setup the correct transfer code for this transfer. + * + * This call updates all the necessary state information if successful, + * so the caller does not need to do anything more than start the transfer + * as normal, since the IRQ will have been re-routed to the FIQ handler. +*/ +static void s3c24xx_spi_tryfiq(struct s3c24xx_spi *hw) +{ + struct pt_regs regs; + enum spi_fiq_mode mode; + struct spi_fiq_code *code; + u32 *ack_ptr = NULL; + int ret; + + if (!hw->fiq_claimed) { + /* try and claim fiq if we haven't got it, and if not + * then return and simply use another transfer method */ + + ret = claim_fiq(&hw->fiq_handler); + if (ret) + return; + } + + if (hw->tx && !hw->rx) + mode = FIQ_MODE_TX; + else if (hw->rx && !hw->tx) + mode = FIQ_MODE_RX; + else + mode = FIQ_MODE_TXRX; + + regs.uregs[fiq_rspi] = (long)hw->regs; + regs.uregs[fiq_rrx] = (long)hw->rx; + regs.uregs[fiq_rtx] = (long)hw->tx + 1; + regs.uregs[fiq_rcount] = hw->len - 1; + + set_fiq_regs(®s); + + if (hw->fiq_mode != mode) { + hw->fiq_mode = mode; + + switch (mode) { + case FIQ_MODE_TX: + code = &s3c24xx_spi_fiq_tx; + break; + case FIQ_MODE_RX: + code = &s3c24xx_spi_fiq_rx; + break; + case FIQ_MODE_TXRX: + code = &s3c24xx_spi_fiq_txrx; + break; + default: + code = NULL; + } + + BUG_ON(!code); + + ack_ptr = (u32 *)&code->data[code->ack_offset]; + set_fiq_handler(&code->data, code->length); + } + + s3c24xx_set_fiq(hw->irq, ack_ptr, true); + + hw->fiq_mode = mode; + hw->fiq_inuse = 1; +} + +/** + * s3c24xx_spi_fiqop - FIQ core code callback + * @pw: Data registered with the handler + * @release: Whether this is a release or a return. + * + * Called by the FIQ code when another module wants to use the FIQ, so + * return whether we are currently using this or not and then update our + * internal state. + */ +static int s3c24xx_spi_fiqop(void *pw, int release) +{ + struct s3c24xx_spi *hw = pw; + int ret = 0; + + if (release) { + if (hw->fiq_inuse) + ret = -EBUSY; + + /* note, we do not need to unroute the FIQ, as the FIQ + * vector code de-routes it to signal the end of transfer */ + + hw->fiq_mode = FIQ_MODE_NONE; + hw->fiq_claimed = 0; + } else { + hw->fiq_claimed = 1; + } + + return ret; +} + +/** + * s3c24xx_spi_initfiq - setup the information for the FIQ core + * @hw: The hardware state. + * + * Setup the fiq_handler block to pass to the FIQ core. + */ +static inline void s3c24xx_spi_initfiq(struct s3c24xx_spi *hw) +{ + hw->fiq_handler.dev_id = hw; + hw->fiq_handler.name = dev_name(hw->dev); + hw->fiq_handler.fiq_op = s3c24xx_spi_fiqop; +} + +/** + * s3c24xx_spi_usefiq - return if we should be using FIQ. + * @hw: The hardware state. + * + * Return true if the platform data specifies whether this channel is + * allowed to use the FIQ. + */ +static inline bool s3c24xx_spi_usefiq(struct s3c24xx_spi *hw) +{ + return hw->pdata->use_fiq; +} + +/** + * s3c24xx_spi_usingfiq - return if channel is using FIQ + * @spi: The hardware state. + * + * Return whether the channel is currently using the FIQ (separate from + * whether the FIQ is claimed). + */ +static inline bool s3c24xx_spi_usingfiq(struct s3c24xx_spi *spi) +{ + return spi->fiq_inuse; +} +#else + +static inline void s3c24xx_spi_initfiq(struct s3c24xx_spi *s) { } +static inline void s3c24xx_spi_tryfiq(struct s3c24xx_spi *s) { } +static inline bool s3c24xx_spi_usefiq(struct s3c24xx_spi *s) { return false; } +static inline bool s3c24xx_spi_usingfiq(struct s3c24xx_spi *s) { return false; } + +#endif /* CONFIG_SPI_S3C24XX_FIQ */ + +static int s3c24xx_spi_txrx(struct spi_device *spi, struct spi_transfer *t) +{ + struct s3c24xx_spi *hw = to_hw(spi); + + hw->tx = t->tx_buf; + hw->rx = t->rx_buf; + hw->len = t->len; + hw->count = 0; + + init_completion(&hw->done); + + hw->fiq_inuse = 0; + if (s3c24xx_spi_usefiq(hw) && t->len >= 3) + s3c24xx_spi_tryfiq(hw); + + /* send the first byte */ + writeb(hw_txbyte(hw, 0), hw->regs + S3C2410_SPTDAT); + + wait_for_completion(&hw->done); + return hw->count; +} + +static irqreturn_t s3c24xx_spi_irq(int irq, void *dev) +{ + struct s3c24xx_spi *hw = dev; + unsigned int spsta = readb(hw->regs + S3C2410_SPSTA); + unsigned int count = hw->count; + + if (spsta & S3C2410_SPSTA_DCOL) { + dev_dbg(hw->dev, "data-collision\n"); + complete(&hw->done); + goto irq_done; + } + + if (!(spsta & S3C2410_SPSTA_READY)) { + dev_dbg(hw->dev, "spi not ready for tx?\n"); + complete(&hw->done); + goto irq_done; + } + + if (!s3c24xx_spi_usingfiq(hw)) { + hw->count++; + + if (hw->rx) + hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT); + + count++; + + if (count < hw->len) + writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT); + else + complete(&hw->done); + } else { + hw->count = hw->len; + hw->fiq_inuse = 0; + + if (hw->rx) + hw->rx[hw->len-1] = readb(hw->regs + S3C2410_SPRDAT); + + complete(&hw->done); + } + + irq_done: + return IRQ_HANDLED; +} + +static void s3c24xx_spi_initialsetup(struct s3c24xx_spi *hw) +{ + /* for the moment, permanently enable the clock */ + + clk_enable(hw->clk); + + /* program defaults into the registers */ + + writeb(0xff, hw->regs + S3C2410_SPPRE); + writeb(SPPIN_DEFAULT, hw->regs + S3C2410_SPPIN); + writeb(SPCON_DEFAULT, hw->regs + S3C2410_SPCON); +} + +static int s3c24xx_spi_probe(struct platform_device *pdev) +{ + struct s3c2410_spi_info *pdata; + struct s3c24xx_spi *hw; + struct spi_master *master; + int err = 0; + + master = devm_spi_alloc_master(&pdev->dev, sizeof(struct s3c24xx_spi)); + if (master == NULL) { + dev_err(&pdev->dev, "No memory for spi_master\n"); + return -ENOMEM; + } + + hw = spi_master_get_devdata(master); + + hw->master = master; + hw->pdata = pdata = dev_get_platdata(&pdev->dev); + hw->dev = &pdev->dev; + + if (pdata == NULL) { + dev_err(&pdev->dev, "No platform data supplied\n"); + return -ENOENT; + } + + platform_set_drvdata(pdev, hw); + init_completion(&hw->done); + + /* initialise fiq handler */ + + s3c24xx_spi_initfiq(hw); + + /* setup the master state. */ + + /* the spi->mode bits understood by this driver: */ + master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH; + + master->num_chipselect = hw->pdata->num_cs; + master->bus_num = pdata->bus_num; + master->bits_per_word_mask = SPI_BPW_MASK(8); + /* we need to call the local chipselect callback */ + master->flags = SPI_MASTER_GPIO_SS; + master->use_gpio_descriptors = true; + + /* setup the state for the bitbang driver */ + + hw->bitbang.master = hw->master; + hw->bitbang.setup_transfer = s3c24xx_spi_setupxfer; + hw->bitbang.chipselect = s3c24xx_spi_chipsel; + hw->bitbang.txrx_bufs = s3c24xx_spi_txrx; + + hw->master->setup = s3c24xx_spi_setup; + + dev_dbg(hw->dev, "bitbang at %p\n", &hw->bitbang); + + /* find and map our resources */ + hw->regs = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(hw->regs)) + return PTR_ERR(hw->regs); + + hw->irq = platform_get_irq(pdev, 0); + if (hw->irq < 0) + return -ENOENT; + + err = devm_request_irq(&pdev->dev, hw->irq, s3c24xx_spi_irq, 0, + pdev->name, hw); + if (err) { + dev_err(&pdev->dev, "Cannot claim IRQ\n"); + return err; + } + + hw->clk = devm_clk_get(&pdev->dev, "spi"); + if (IS_ERR(hw->clk)) { + dev_err(&pdev->dev, "No clock for device\n"); + return PTR_ERR(hw->clk); + } + + s3c24xx_spi_initialsetup(hw); + + /* register our spi controller */ + + err = spi_bitbang_start(&hw->bitbang); + if (err) { + dev_err(&pdev->dev, "Failed to register SPI master\n"); + goto err_register; + } + + return 0; + + err_register: + clk_disable(hw->clk); + + return err; +} + +static int s3c24xx_spi_remove(struct platform_device *dev) +{ + struct s3c24xx_spi *hw = platform_get_drvdata(dev); + + spi_bitbang_stop(&hw->bitbang); + clk_disable(hw->clk); + spi_master_put(hw->master); + return 0; +} + + +#ifdef CONFIG_PM + +static int s3c24xx_spi_suspend(struct device *dev) +{ + struct s3c24xx_spi *hw = dev_get_drvdata(dev); + int ret; + + ret = spi_master_suspend(hw->master); + if (ret) + return ret; + + clk_disable(hw->clk); + return 0; +} + +static int s3c24xx_spi_resume(struct device *dev) +{ + struct s3c24xx_spi *hw = dev_get_drvdata(dev); + + s3c24xx_spi_initialsetup(hw); + return spi_master_resume(hw->master); +} + +static const struct dev_pm_ops s3c24xx_spi_pmops = { + .suspend = s3c24xx_spi_suspend, + .resume = s3c24xx_spi_resume, +}; + +#define S3C24XX_SPI_PMOPS &s3c24xx_spi_pmops +#else +#define S3C24XX_SPI_PMOPS NULL +#endif /* CONFIG_PM */ + +MODULE_ALIAS("platform:s3c2410-spi"); +static struct platform_driver s3c24xx_spi_driver = { + .probe = s3c24xx_spi_probe, + .remove = s3c24xx_spi_remove, + .driver = { + .name = "s3c2410-spi", + .pm = S3C24XX_SPI_PMOPS, + }, +}; +module_platform_driver(s3c24xx_spi_driver); + +MODULE_DESCRIPTION("S3C24XX SPI Driver"); +MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>"); +MODULE_LICENSE("GPL"); |