/*
* MPC52xx SPI bus driver.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/of_platform.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/spi/spi.h>
#include <linux/io.h>
#include <linux/of_gpio.h>
#include <linux/slab.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;
unsigned int *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;
gpio_set_value(ms->gpio_cs[cs], value ? 0 : 1);
} 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 = get_tbl();
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 != NO_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 += get_tbl() - ms->wcol_tx_timestamp;
ms->wcol_tx_timestamp = get_tbl();
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;
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 = get_tbl();
ms->timestamp += ms->transfer->delay_usecs * tb_ticks_per_usec;
ms->state = mpc52xx_spi_fsmstate_wait;
return FSM_CONTINUE;
}
/* Write out the next byte */
ms->wcol_tx_timestamp = get_tbl();
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)get_tbl()) - 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;
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 = conta
