diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/spi/spi-mpc52xx.c | 550 |
1 files changed, 550 insertions, 0 deletions
diff --git a/drivers/spi/spi-mpc52xx.c b/drivers/spi/spi-mpc52xx.c new file mode 100644 index 000000000..7b64e64c6 --- /dev/null +++ b/drivers/spi/spi-mpc52xx.c @@ -0,0 +1,550 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * MPC52xx SPI bus driver. + * + * Copyright (C) 2008 Secret Lab Technologies Ltd. + * + * This is the driver for the MPC5200's dedicated SPI controller. + * + * Note: this driver does not support the MPC5200 PSC in SPI mode. For + * that driver see drivers/spi/mpc52xx_psc_spi.c + */ + +#include <linux/module.h> +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/of_platform.h> +#include <linux/interrupt.h> +#include <linux/delay.h> +#include <linux/gpio/consumer.h> +#include <linux/spi/spi.h> +#include <linux/io.h> +#include <linux/slab.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> + +#include <asm/time.h> +#include <asm/mpc52xx.h> + +MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); +MODULE_DESCRIPTION("MPC52xx SPI (non-PSC) Driver"); +MODULE_LICENSE("GPL"); + +/* Register offsets */ +#define SPI_CTRL1 0x00 +#define SPI_CTRL1_SPIE (1 << 7) +#define SPI_CTRL1_SPE (1 << 6) +#define SPI_CTRL1_MSTR (1 << 4) +#define SPI_CTRL1_CPOL (1 << 3) +#define SPI_CTRL1_CPHA (1 << 2) +#define SPI_CTRL1_SSOE (1 << 1) +#define SPI_CTRL1_LSBFE (1 << 0) + +#define SPI_CTRL2 0x01 +#define SPI_BRR 0x04 + +#define SPI_STATUS 0x05 +#define SPI_STATUS_SPIF (1 << 7) +#define SPI_STATUS_WCOL (1 << 6) +#define SPI_STATUS_MODF (1 << 4) + +#define SPI_DATA 0x09 +#define SPI_PORTDATA 0x0d +#define SPI_DATADIR 0x10 + +/* FSM state return values */ +#define FSM_STOP 0 /* Nothing more for the state machine to */ + /* do. If something interesting happens */ + /* then an IRQ will be received */ +#define FSM_POLL 1 /* need to poll for completion, an IRQ is */ + /* not expected */ +#define FSM_CONTINUE 2 /* Keep iterating the state machine */ + +/* Driver internal data */ +struct mpc52xx_spi { + struct spi_master *master; + void __iomem *regs; + int irq0; /* MODF irq */ + int irq1; /* SPIF irq */ + unsigned int ipb_freq; + + /* Statistics; not used now, but will be reintroduced for debugfs */ + int msg_count; + int wcol_count; + int wcol_ticks; + u32 wcol_tx_timestamp; + int modf_count; + int byte_count; + + struct list_head queue; /* queue of pending messages */ + spinlock_t lock; + struct work_struct work; + + /* Details of current transfer (length, and buffer pointers) */ + struct spi_message *message; /* current message */ + struct spi_transfer *transfer; /* current transfer */ + int (*state)(int irq, struct mpc52xx_spi *ms, u8 status, u8 data); + int len; + int timestamp; + u8 *rx_buf; + const u8 *tx_buf; + int cs_change; + int gpio_cs_count; + struct gpio_desc **gpio_cs; +}; + +/* + * CS control function + */ +static void mpc52xx_spi_chipsel(struct mpc52xx_spi *ms, int value) +{ + int cs; + + if (ms->gpio_cs_count > 0) { + cs = ms->message->spi->chip_select; + gpiod_set_value(ms->gpio_cs[cs], value); + } else { + out_8(ms->regs + SPI_PORTDATA, value ? 0 : 0x08); + } +} + +/* + * Start a new transfer. This is called both by the idle state + * for the first transfer in a message, and by the wait state when the + * previous transfer in a message is complete. + */ +static void mpc52xx_spi_start_transfer(struct mpc52xx_spi *ms) +{ + ms->rx_buf = ms->transfer->rx_buf; + ms->tx_buf = ms->transfer->tx_buf; + ms->len = ms->transfer->len; + + /* Activate the chip select */ + if (ms->cs_change) + mpc52xx_spi_chipsel(ms, 1); + ms->cs_change = ms->transfer->cs_change; + + /* Write out the first byte */ + ms->wcol_tx_timestamp = mftb(); + if (ms->tx_buf) + out_8(ms->regs + SPI_DATA, *ms->tx_buf++); + else + out_8(ms->regs + SPI_DATA, 0); +} + +/* Forward declaration of state handlers */ +static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms, + u8 status, u8 data); +static int mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, + u8 status, u8 data); + +/* + * IDLE state + * + * No transfers are in progress; if another transfer is pending then retrieve + * it and kick it off. Otherwise, stop processing the state machine + */ +static int +mpc52xx_spi_fsmstate_idle(int irq, struct mpc52xx_spi *ms, u8 status, u8 data) +{ + struct spi_device *spi; + int spr, sppr; + u8 ctrl1; + + if (status && irq) + dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n", + status); + + /* Check if there is another transfer waiting. */ + if (list_empty(&ms->queue)) + return FSM_STOP; + + /* get the head of the queue */ + ms->message = list_first_entry(&ms->queue, struct spi_message, queue); + list_del_init(&ms->message->queue); + + /* Setup the controller parameters */ + ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR; + spi = ms->message->spi; + if (spi->mode & SPI_CPHA) + ctrl1 |= SPI_CTRL1_CPHA; + if (spi->mode & SPI_CPOL) + ctrl1 |= SPI_CTRL1_CPOL; + if (spi->mode & SPI_LSB_FIRST) + ctrl1 |= SPI_CTRL1_LSBFE; + out_8(ms->regs + SPI_CTRL1, ctrl1); + + /* Setup the controller speed */ + /* minimum divider is '2'. Also, add '1' to force rounding the + * divider up. */ + sppr = ((ms->ipb_freq / ms->message->spi->max_speed_hz) + 1) >> 1; + spr = 0; + if (sppr < 1) + sppr = 1; + while (((sppr - 1) & ~0x7) != 0) { + sppr = (sppr + 1) >> 1; /* add '1' to force rounding up */ + spr++; + } + sppr--; /* sppr quantity in register is offset by 1 */ + if (spr > 7) { + /* Don't overrun limits of SPI baudrate register */ + spr = 7; + sppr = 7; + } + out_8(ms->regs + SPI_BRR, sppr << 4 | spr); /* Set speed */ + + ms->cs_change = 1; + ms->transfer = container_of(ms->message->transfers.next, + struct spi_transfer, transfer_list); + + mpc52xx_spi_start_transfer(ms); + ms->state = mpc52xx_spi_fsmstate_transfer; + + return FSM_CONTINUE; +} + +/* + * TRANSFER state + * + * In the middle of a transfer. If the SPI core has completed processing + * a byte, then read out the received data and write out the next byte + * (unless this transfer is finished; in which case go on to the wait + * state) + */ +static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms, + u8 status, u8 data) +{ + if (!status) + return ms->irq0 ? FSM_STOP : FSM_POLL; + + if (status & SPI_STATUS_WCOL) { + /* The SPI controller is stoopid. At slower speeds, it may + * raise the SPIF flag before the state machine is actually + * finished, which causes a collision (internal to the state + * machine only). The manual recommends inserting a delay + * between receiving the interrupt and sending the next byte, + * but it can also be worked around simply by retrying the + * transfer which is what we do here. */ + ms->wcol_count++; + ms->wcol_ticks += mftb() - ms->wcol_tx_timestamp; + ms->wcol_tx_timestamp = mftb(); + data = 0; + if (ms->tx_buf) + data = *(ms->tx_buf - 1); + out_8(ms->regs + SPI_DATA, data); /* try again */ + return FSM_CONTINUE; + } else if (status & SPI_STATUS_MODF) { + ms->modf_count++; + dev_err(&ms->master->dev, "mode fault\n"); + mpc52xx_spi_chipsel(ms, 0); + ms->message->status = -EIO; + if (ms->message->complete) + ms->message->complete(ms->message->context); + ms->state = mpc52xx_spi_fsmstate_idle; + return FSM_CONTINUE; + } + + /* Read data out of the spi device */ + ms->byte_count++; + if (ms->rx_buf) + *ms->rx_buf++ = data; + + /* Is the transfer complete? */ + ms->len--; + if (ms->len == 0) { + ms->timestamp = mftb(); + if (ms->transfer->delay.unit == SPI_DELAY_UNIT_USECS) + ms->timestamp += ms->transfer->delay.value * + tb_ticks_per_usec; + ms->state = mpc52xx_spi_fsmstate_wait; + return FSM_CONTINUE; + } + + /* Write out the next byte */ + ms->wcol_tx_timestamp = mftb(); + if (ms->tx_buf) + out_8(ms->regs + SPI_DATA, *ms->tx_buf++); + else + out_8(ms->regs + SPI_DATA, 0); + + return FSM_CONTINUE; +} + +/* + * WAIT state + * + * A transfer has completed; need to wait for the delay period to complete + * before starting the next transfer + */ +static int +mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, u8 status, u8 data) +{ + if (status && irq) + dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n", + status); + + if (((int)mftb()) - ms->timestamp < 0) + return FSM_POLL; + + ms->message->actual_length += ms->transfer->len; + + /* Check if there is another transfer in this message. If there + * aren't then deactivate CS, notify sender, and drop back to idle + * to start the next message. */ + if (ms->transfer->transfer_list.next == &ms->message->transfers) { + ms->msg_count++; + mpc52xx_spi_chipsel(ms, 0); + ms->message->status = 0; + if (ms->message->complete) + ms->message->complete(ms->message->context); + ms->state = mpc52xx_spi_fsmstate_idle; + return FSM_CONTINUE; + } + + /* There is another transfer; kick it off */ + + if (ms->cs_change) + mpc52xx_spi_chipsel(ms, 0); + + ms->transfer = container_of(ms->transfer->transfer_list.next, + struct spi_transfer, transfer_list); + mpc52xx_spi_start_transfer(ms); + ms->state = mpc52xx_spi_fsmstate_transfer; + return FSM_CONTINUE; +} + +/** + * mpc52xx_spi_fsm_process - Finite State Machine iteration function + * @irq: irq number that triggered the FSM or 0 for polling + * @ms: pointer to mpc52xx_spi driver data + */ +static void mpc52xx_spi_fsm_process(int irq, struct mpc52xx_spi *ms) +{ + int rc = FSM_CONTINUE; + u8 status, data; + + while (rc == FSM_CONTINUE) { + /* Interrupt cleared by read of STATUS followed by + * read of DATA registers */ + status = in_8(ms->regs + SPI_STATUS); + data = in_8(ms->regs + SPI_DATA); + rc = ms->state(irq, ms, status, data); + } + + if (rc == FSM_POLL) + schedule_work(&ms->work); +} + +/** + * mpc52xx_spi_irq - IRQ handler + */ +static irqreturn_t mpc52xx_spi_irq(int irq, void *_ms) +{ + struct mpc52xx_spi *ms = _ms; + spin_lock(&ms->lock); + mpc52xx_spi_fsm_process(irq, ms); + spin_unlock(&ms->lock); + return IRQ_HANDLED; +} + +/** + * mpc52xx_spi_wq - Workqueue function for polling the state machine + */ +static void mpc52xx_spi_wq(struct work_struct *work) +{ + struct mpc52xx_spi *ms = container_of(work, struct mpc52xx_spi, work); + unsigned long flags; + + spin_lock_irqsave(&ms->lock, flags); + mpc52xx_spi_fsm_process(0, ms); + spin_unlock_irqrestore(&ms->lock, flags); +} + +/* + * spi_master ops + */ + +static int mpc52xx_spi_transfer(struct spi_device *spi, struct spi_message *m) +{ + struct mpc52xx_spi *ms = spi_master_get_devdata(spi->master); + unsigned long flags; + + m->actual_length = 0; + m->status = -EINPROGRESS; + + spin_lock_irqsave(&ms->lock, flags); + list_add_tail(&m->queue, &ms->queue); + spin_unlock_irqrestore(&ms->lock, flags); + schedule_work(&ms->work); + + return 0; +} + +/* + * OF Platform Bus Binding + */ +static int mpc52xx_spi_probe(struct platform_device *op) +{ + struct spi_master *master; + struct mpc52xx_spi *ms; + struct gpio_desc *gpio_cs; + void __iomem *regs; + u8 ctrl1; + int rc, i = 0; + + /* MMIO registers */ + dev_dbg(&op->dev, "probing mpc5200 SPI device\n"); + regs = of_iomap(op->dev.of_node, 0); + if (!regs) + return -ENODEV; + + /* initialize the device */ + ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR; + out_8(regs + SPI_CTRL1, ctrl1); + out_8(regs + SPI_CTRL2, 0x0); + out_8(regs + SPI_DATADIR, 0xe); /* Set output pins */ + out_8(regs + SPI_PORTDATA, 0x8); /* Deassert /SS signal */ + + /* Clear the status register and re-read it to check for a MODF + * failure. This driver cannot currently handle multiple masters + * on the SPI bus. This fault will also occur if the SPI signals + * are not connected to any pins (port_config setting) */ + in_8(regs + SPI_STATUS); + out_8(regs + SPI_CTRL1, ctrl1); + + in_8(regs + SPI_DATA); + if (in_8(regs + SPI_STATUS) & SPI_STATUS_MODF) { + dev_err(&op->dev, "mode fault; is port_config correct?\n"); + rc = -EIO; + goto err_init; + } + + dev_dbg(&op->dev, "allocating spi_master struct\n"); + master = spi_alloc_master(&op->dev, sizeof(*ms)); + if (!master) { + rc = -ENOMEM; + goto err_alloc; + } + + master->transfer = mpc52xx_spi_transfer; + master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST; + master->bits_per_word_mask = SPI_BPW_MASK(8); + master->dev.of_node = op->dev.of_node; + + platform_set_drvdata(op, master); + + ms = spi_master_get_devdata(master); + ms->master = master; + ms->regs = regs; + ms->irq0 = irq_of_parse_and_map(op->dev.of_node, 0); + ms->irq1 = irq_of_parse_and_map(op->dev.of_node, 1); + ms->state = mpc52xx_spi_fsmstate_idle; + ms->ipb_freq = mpc5xxx_get_bus_frequency(&op->dev); + ms->gpio_cs_count = gpiod_count(&op->dev, NULL); + if (ms->gpio_cs_count > 0) { + master->num_chipselect = ms->gpio_cs_count; + ms->gpio_cs = kmalloc_array(ms->gpio_cs_count, + sizeof(*ms->gpio_cs), + GFP_KERNEL); + if (!ms->gpio_cs) { + rc = -ENOMEM; + goto err_alloc_gpio; + } + + for (i = 0; i < ms->gpio_cs_count; i++) { + gpio_cs = gpiod_get_index(&op->dev, + NULL, i, GPIOD_OUT_LOW); + rc = PTR_ERR_OR_ZERO(gpio_cs); + if (rc) { + dev_err(&op->dev, + "failed to get spi cs gpio #%d: %d\n", + i, rc); + goto err_gpio; + } + + ms->gpio_cs[i] = gpio_cs; + } + } + + spin_lock_init(&ms->lock); + INIT_LIST_HEAD(&ms->queue); + INIT_WORK(&ms->work, mpc52xx_spi_wq); + + /* Decide if interrupts can be used */ + if (ms->irq0 && ms->irq1) { + rc = request_irq(ms->irq0, mpc52xx_spi_irq, 0, + "mpc5200-spi-modf", ms); + rc |= request_irq(ms->irq1, mpc52xx_spi_irq, 0, + "mpc5200-spi-spif", ms); + if (rc) { + free_irq(ms->irq0, ms); + free_irq(ms->irq1, ms); + ms->irq0 = ms->irq1 = 0; + } + } else { + /* operate in polled mode */ + ms->irq0 = ms->irq1 = 0; + } + + if (!ms->irq0) + dev_info(&op->dev, "using polled mode\n"); + + dev_dbg(&op->dev, "registering spi_master struct\n"); + rc = spi_register_master(master); + if (rc) + goto err_register; + + dev_info(&ms->master->dev, "registered MPC5200 SPI bus\n"); + + return rc; + + err_register: + dev_err(&ms->master->dev, "initialization failed\n"); + err_gpio: + while (i-- > 0) + gpiod_put(ms->gpio_cs[i]); + + kfree(ms->gpio_cs); + err_alloc_gpio: + spi_master_put(master); + err_alloc: + err_init: + iounmap(regs); + return rc; +} + +static int mpc52xx_spi_remove(struct platform_device *op) +{ + struct spi_master *master = spi_master_get(platform_get_drvdata(op)); + struct mpc52xx_spi *ms = spi_master_get_devdata(master); + int i; + + free_irq(ms->irq0, ms); + free_irq(ms->irq1, ms); + + for (i = 0; i < ms->gpio_cs_count; i++) + gpiod_put(ms->gpio_cs[i]); + + kfree(ms->gpio_cs); + spi_unregister_master(master); + iounmap(ms->regs); + spi_master_put(master); + + return 0; +} + +static const struct of_device_id mpc52xx_spi_match[] = { + { .compatible = "fsl,mpc5200-spi", }, + {} +}; +MODULE_DEVICE_TABLE(of, mpc52xx_spi_match); + +static struct platform_driver mpc52xx_spi_of_driver = { + .driver = { + .name = "mpc52xx-spi", + .of_match_table = mpc52xx_spi_match, + }, + .probe = mpc52xx_spi_probe, + .remove = mpc52xx_spi_remove, +}; +module_platform_driver(mpc52xx_spi_of_driver); |