diff options
Diffstat (limited to 'target/linux/ramips/files-3.7/drivers/spi/spi-ramips.c')
-rw-r--r-- | target/linux/ramips/files-3.7/drivers/spi/spi-ramips.c | 559 |
1 files changed, 559 insertions, 0 deletions
diff --git a/target/linux/ramips/files-3.7/drivers/spi/spi-ramips.c b/target/linux/ramips/files-3.7/drivers/spi/spi-ramips.c new file mode 100644 index 0000000..d2ceaf3 --- /dev/null +++ b/target/linux/ramips/files-3.7/drivers/spi/spi-ramips.c @@ -0,0 +1,559 @@ +/* + * ramips_spi.c -- Ralink RT288x/RT305x SPI controller driver + * + * Copyright (C) 2011 Sergiy <piratfm@gmail.com> + * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org> + * + * 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/init.h> +#include <linux/module.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/delay.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/spi/spi.h> + +#define DRIVER_NAME "ramips-spi" +#define RALINK_NUM_CHIPSELECTS 1 /* only one slave is supported*/ +#define RALINK_SPI_WAIT_RDY_MAX_LOOP 2000 /* in usec */ + +#define RAMIPS_SPI_STAT 0x00 +#define RAMIPS_SPI_CFG 0x10 +#define RAMIPS_SPI_CTL 0x14 +#define RAMIPS_SPI_DATA 0x20 + +/* SPISTAT register bit field */ +#define SPISTAT_BUSY BIT(0) + +/* SPICFG register bit field */ +#define SPICFG_LSBFIRST 0 +#define SPICFG_MSBFIRST BIT(8) +#define SPICFG_SPICLKPOL BIT(6) +#define SPICFG_RXCLKEDGE_FALLING BIT(5) +#define SPICFG_TXCLKEDGE_FALLING BIT(4) +#define SPICFG_SPICLK_PRESCALE_MASK 0x7 +#define SPICFG_SPICLK_DIV2 0 +#define SPICFG_SPICLK_DIV4 1 +#define SPICFG_SPICLK_DIV8 2 +#define SPICFG_SPICLK_DIV16 3 +#define SPICFG_SPICLK_DIV32 4 +#define SPICFG_SPICLK_DIV64 5 +#define SPICFG_SPICLK_DIV128 6 +#define SPICFG_SPICLK_DISABLE 7 + +/* SPICTL register bit field */ +#define SPICTL_HIZSDO BIT(3) +#define SPICTL_STARTWR BIT(2) +#define SPICTL_STARTRD BIT(1) +#define SPICTL_SPIENA BIT(0) + +#ifdef DEBUG +#define spi_debug(args...) printk(args) +#else +#define spi_debug(args...) +#endif + +struct ramips_spi { + struct work_struct work; + + /* Lock access to transfer list.*/ + spinlock_t lock; + + struct list_head msg_queue; + struct spi_master *master; + void __iomem *base; + unsigned int sys_freq; + unsigned int speed; + + struct clk *clk; +}; + +static struct workqueue_struct *ramips_spi_wq; + +static inline struct ramips_spi *ramips_spidev_to_rs(struct spi_device *spi) +{ + return spi_master_get_devdata(spi->master); +} + +static inline u32 ramips_spi_read(struct ramips_spi *rs, u32 reg) +{ + return ioread32(rs->base + reg); +} + +static inline void ramips_spi_write(struct ramips_spi *rs, u32 reg, u32 val) +{ + iowrite32(val, rs->base + reg); +} + +static inline void ramips_spi_setbits(struct ramips_spi *rs, u32 reg, u32 mask) +{ + void __iomem *addr = rs->base + reg; + u32 val; + + val = ioread32(addr); + val |= mask; + iowrite32(val, addr); +} + +static inline void ramips_spi_clrbits(struct ramips_spi *rs, u32 reg, u32 mask) +{ + void __iomem *addr = rs->base + reg; + u32 val; + + val = ioread32(addr); + val &= ~mask; + iowrite32(val, addr); +} + +static int ramips_spi_baudrate_set(struct spi_device *spi, unsigned int speed) +{ + struct ramips_spi *rs = ramips_spidev_to_rs(spi); + u32 rate; + u32 prescale; + u32 reg; + + spi_debug("%s: speed:%u\n", __func__, speed); + + /* + * the supported rates are: 2,4,8...128 + * round up as we look for equal or less speed + */ + rate = DIV_ROUND_UP(rs->sys_freq, speed); + spi_debug("%s: rate-1:%u\n", __func__, rate); + rate = roundup_pow_of_two(rate); + spi_debug("%s: rate-2:%u\n", __func__, rate); + + /* check if requested speed is too small */ + if (rate > 128) + return -EINVAL; + + if (rate < 2) + rate = 2; + + /* Convert the rate to SPI clock divisor value. */ + prescale = ilog2(rate/2); + spi_debug("%s: prescale:%u\n", __func__, prescale); + + reg = ramips_spi_read(rs, RAMIPS_SPI_CFG); + reg = ((reg & ~SPICFG_SPICLK_PRESCALE_MASK) | prescale); + ramips_spi_write(rs, RAMIPS_SPI_CFG, reg); + rs->speed = speed; + return 0; +} + +/* + * called only when no transfer is active on the bus + */ +static int +ramips_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t) +{ + struct ramips_spi *rs = ramips_spidev_to_rs(spi); + unsigned int speed = spi->max_speed_hz; + int rc; + unsigned int bits_per_word = 8; + + if ((t != NULL) && t->speed_hz) + speed = t->speed_hz; + + if ((t != NULL) && t->bits_per_word) + bits_per_word = t->bits_per_word; + + if (rs->speed != speed) { + spi_debug("%s: speed_hz:%u\n", __func__, speed); + rc = ramips_spi_baudrate_set(spi, speed); + if (rc) + return rc; + } + + if (bits_per_word != 8) { + spi_debug("%s: bad bits_per_word: %u\n", __func__, + bits_per_word); + return -EINVAL; + } + + return 0; +} + +static void ramips_spi_set_cs(struct ramips_spi *rs, int enable) +{ + if (enable) + ramips_spi_clrbits(rs, RAMIPS_SPI_CTL, SPICTL_SPIENA); + else + ramips_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_SPIENA); +} + +static inline int ramips_spi_wait_till_ready(struct ramips_spi *rs) +{ + int i; + + for (i = 0; i < RALINK_SPI_WAIT_RDY_MAX_LOOP; i++) { + u32 status; + + status = ramips_spi_read(rs, RAMIPS_SPI_STAT); + if ((status & SPISTAT_BUSY) == 0) + return 0; + + udelay(1); + } + + return -ETIMEDOUT; +} + +static unsigned int +ramips_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer) +{ + struct ramips_spi *rs = ramips_spidev_to_rs(spi); + unsigned count = 0; + u8 *rx = xfer->rx_buf; + const u8 *tx = xfer->tx_buf; + int err; + + spi_debug("%s(%d): %s %s\n", __func__, xfer->len, + (tx != NULL) ? "tx" : " ", + (rx != NULL) ? "rx" : " "); + + if (tx) { + for (count = 0; count < xfer->len; count++) { + ramips_spi_write(rs, RAMIPS_SPI_DATA, tx[count]); + ramips_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_STARTWR); + err = ramips_spi_wait_till_ready(rs); + if (err) { + dev_err(&spi->dev, "TX failed, err=%d\n", err); + goto out; + } + } + } + + if (rx) { + for (count = 0; count < xfer->len; count++) { + ramips_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_STARTRD); + err = ramips_spi_wait_till_ready(rs); + if (err) { + dev_err(&spi->dev, "RX failed, err=%d\n", err); + goto out; + } + rx[count] = (u8) ramips_spi_read(rs, RAMIPS_SPI_DATA); + } + } + +out: + return count; +} + +static void ramips_spi_work(struct work_struct *work) +{ + struct ramips_spi *rs = + container_of(work, struct ramips_spi, work); + + spin_lock_irq(&rs->lock); + while (!list_empty(&rs->msg_queue)) { + struct spi_message *m; + struct spi_device *spi; + struct spi_transfer *t = NULL; + int par_override = 0; + int status = 0; + int cs_active = 0; + + m = container_of(rs->msg_queue.next, struct spi_message, + queue); + + list_del_init(&m->queue); + spin_unlock_irq(&rs->lock); + + spi = m->spi; + + /* Load defaults */ + status = ramips_spi_setup_transfer(spi, NULL); + + if (status < 0) + goto msg_done; + + list_for_each_entry(t, &m->transfers, transfer_list) { + if (par_override || t->speed_hz || t->bits_per_word) { + par_override = 1; + status = ramips_spi_setup_transfer(spi, t); + if (status < 0) + break; + if (!t->speed_hz && !t->bits_per_word) + par_override = 0; + } + + if (!cs_active) { + ramips_spi_set_cs(rs, 1); + cs_active = 1; + } + + if (t->len) + m->actual_length += + ramips_spi_write_read(spi, t); + + if (t->delay_usecs) + udelay(t->delay_usecs); + + if (t->cs_change) { + ramips_spi_set_cs(rs, 0); + cs_active = 0; + } + } + +msg_done: + if (cs_active) + ramips_spi_set_cs(rs, 0); + + m->status = status; + m->complete(m->context); + + spin_lock_irq(&rs->lock); + } + + spin_unlock_irq(&rs->lock); +} + +static int ramips_spi_setup(struct spi_device *spi) +{ + struct ramips_spi *rs = ramips_spidev_to_rs(spi); + + if ((spi->max_speed_hz == 0) || + (spi->max_speed_hz > (rs->sys_freq / 2))) + spi->max_speed_hz = (rs->sys_freq / 2); + + if (spi->max_speed_hz < (rs->sys_freq/128)) { + dev_err(&spi->dev, "setup: requested speed too low %d Hz\n", + spi->max_speed_hz); + return -EINVAL; + } + + if (spi->bits_per_word != 0 && spi->bits_per_word != 8) { + dev_err(&spi->dev, + "setup: requested bits per words - os wrong %d bpw\n", + spi->bits_per_word); + return -EINVAL; + } + + if (spi->bits_per_word == 0) + spi->bits_per_word = 8; + + /* + * baudrate & width will be set ramips_spi_setup_transfer + */ + return 0; +} + +static int ramips_spi_transfer(struct spi_device *spi, struct spi_message *m) +{ + struct ramips_spi *rs; + struct spi_transfer *t = NULL; + unsigned long flags; + + m->actual_length = 0; + m->status = 0; + + /* reject invalid messages and transfers */ + if (list_empty(&m->transfers) || !m->complete) + return -EINVAL; + + rs = ramips_spidev_to_rs(spi); + + list_for_each_entry(t, &m->transfers, transfer_list) { + unsigned int bits_per_word = spi->bits_per_word; + + if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) { + dev_err(&spi->dev, + "message rejected : " + "invalid transfer data buffers\n"); + goto msg_rejected; + } + + if (t->bits_per_word) + bits_per_word = t->bits_per_word; + + if (bits_per_word != 8) { + dev_err(&spi->dev, + "message rejected : " + "invalid transfer bits_per_word (%d bits)\n", + bits_per_word); + goto msg_rejected; + } + + if (t->speed_hz && t->speed_hz < (rs->sys_freq/128)) { + dev_err(&spi->dev, + "message rejected : " + "device min speed (%d Hz) exceeds " + "required transfer speed (%d Hz)\n", + (rs->sys_freq/128), t->speed_hz); + goto msg_rejected; + } + } + + + spin_lock_irqsave(&rs->lock, flags); + list_add_tail(&m->queue, &rs->msg_queue); + queue_work(ramips_spi_wq, &rs->work); + spin_unlock_irqrestore(&rs->lock, flags); + + return 0; +msg_rejected: + /* Message rejected and not queued */ + m->status = -EINVAL; + if (m->complete) + m->complete(m->context); + return -EINVAL; +} + +static void __init ramips_spi_reset(struct ramips_spi *rs) +{ + ramips_spi_write(rs, RAMIPS_SPI_CFG, + SPICFG_MSBFIRST | SPICFG_TXCLKEDGE_FALLING | + SPICFG_SPICLK_DIV16 | SPICFG_SPICLKPOL); + ramips_spi_write(rs, RAMIPS_SPI_CTL, SPICTL_HIZSDO | SPICTL_SPIENA); +} + +static int __init ramips_spi_probe(struct platform_device *pdev) +{ + struct spi_master *master; + struct ramips_spi *rs; + struct resource *r; + int status = 0; + + master = spi_alloc_master(&pdev->dev, sizeof(*rs)); + if (master == NULL) { + dev_dbg(&pdev->dev, "master allocation failed\n"); + return -ENOMEM; + } + + if (pdev->id != -1) + master->bus_num = pdev->id; + + /* we support only mode 0, and no options */ + master->mode_bits = 0; + + master->setup = ramips_spi_setup; + master->transfer = ramips_spi_transfer; + master->num_chipselect = RALINK_NUM_CHIPSELECTS; + + dev_set_drvdata(&pdev->dev, master); + + rs = spi_master_get_devdata(master); + rs->master = master; + + rs->clk = clk_get(NULL, "sys"); + if (IS_ERR(rs->clk)) { + status = PTR_ERR(rs->clk); + dev_err(&pdev->dev, "unable to get SYS clock, err=%d\n", + status); + goto out_put_master; + } + + status = clk_enable(rs->clk); + if (status) + goto out_put_clk; + + rs->sys_freq = clk_get_rate(rs->clk); + spi_debug("%s: sys_freq: %ld\n", __func__, rs->sys_freq); + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (r == NULL) { + status = -ENODEV; + goto out_disable_clk; + } + + if (!request_mem_region(r->start, (r->end - r->start) + 1, + dev_name(&pdev->dev))) { + status = -EBUSY; + goto out_disable_clk; + } + + rs->base = ioremap(r->start, resource_size(r)); + if (rs->base == NULL) { + dev_err(&pdev->dev, "ioremap failed\n"); + status = -ENOMEM; + goto out_rel_mem; + } + + INIT_WORK(&rs->work, ramips_spi_work); + + spin_lock_init(&rs->lock); + INIT_LIST_HEAD(&rs->msg_queue); + + ramips_spi_reset(rs); + + status = spi_register_master(master); + if (status) + goto out_unmap_base; + + return 0; + +out_unmap_base: + iounmap(rs->base); +out_rel_mem: + release_mem_region(r->start, (r->end - r->start) + 1); +out_disable_clk: + clk_disable(rs->clk); +out_put_clk: + clk_put(rs->clk); +out_put_master: + spi_master_put(master); + return status; +} + +static int ramips_spi_remove(struct platform_device *pdev) +{ + struct spi_master *master; + struct ramips_spi *rs; + struct resource *r; + + master = dev_get_drvdata(&pdev->dev); + rs = spi_master_get_devdata(master); + + cancel_work_sync(&rs->work); + + iounmap(rs->base); + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + release_mem_region(r->start, (r->end - r->start) + 1); + + clk_disable(rs->clk); + clk_put(rs->clk); + spi_unregister_master(master); + + return 0; +} + +MODULE_ALIAS("platform:" DRIVER_NAME); + +static struct platform_driver ramips_spi_driver = { + .driver = { + .name = DRIVER_NAME, + .owner = THIS_MODULE, + }, + .remove = ramips_spi_remove, +}; + +static int __init ramips_spi_init(void) +{ + ramips_spi_wq = create_singlethread_workqueue( + ramips_spi_driver.driver.name); + if (ramips_spi_wq == NULL) + return -ENOMEM; + + return platform_driver_probe(&ramips_spi_driver, ramips_spi_probe); +} +module_init(ramips_spi_init); + +static void __exit ramips_spi_exit(void) +{ + flush_workqueue(ramips_spi_wq); + platform_driver_unregister(&ramips_spi_driver); + + destroy_workqueue(ramips_spi_wq); +} +module_exit(ramips_spi_exit); + +MODULE_DESCRIPTION("Ralink SPI driver"); +MODULE_AUTHOR("Sergiy <piratfm@gmail.com>"); +MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); +MODULE_LICENSE("GPL"); |