u-boot/drivers/spi/exynos_spi.c
Rajeshwari Shinde c4a796329d spi: exynos: Support word transfers
Since SPI register access is so expensive, it is worth transferring data
a word at a time if we can. This complicates the driver unfortunately.

Use the byte-swapping feature to avoid having to convert to/from big
endian in software.

This change increases speed from about 2MB/s to about 4.5MB/s.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Rajeshwari S Shinde <rajeshwari.s@samsung.com>
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
2013-10-08 18:18:12 +05:30

579 lines
15 KiB
C

/*
* (C) Copyright 2012 SAMSUNG Electronics
* Padmavathi Venna <padma.v@samsung.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <malloc.h>
#include <spi.h>
#include <fdtdec.h>
#include <asm/arch/clk.h>
#include <asm/arch/clock.h>
#include <asm/arch/cpu.h>
#include <asm/arch/gpio.h>
#include <asm/arch/pinmux.h>
#include <asm/arch-exynos/spi.h>
#include <asm/io.h>
DECLARE_GLOBAL_DATA_PTR;
/* Information about each SPI controller */
struct spi_bus {
enum periph_id periph_id;
s32 frequency; /* Default clock frequency, -1 for none */
struct exynos_spi *regs;
int inited; /* 1 if this bus is ready for use */
int node;
uint deactivate_delay_us; /* Delay to wait after deactivate */
};
/* A list of spi buses that we know about */
static struct spi_bus spi_bus[EXYNOS5_SPI_NUM_CONTROLLERS];
static unsigned int bus_count;
struct exynos_spi_slave {
struct spi_slave slave;
struct exynos_spi *regs;
unsigned int freq; /* Default frequency */
unsigned int mode;
enum periph_id periph_id; /* Peripheral ID for this device */
unsigned int fifo_size;
int skip_preamble;
struct spi_bus *bus; /* Pointer to our SPI bus info */
ulong last_transaction_us; /* Time of last transaction end */
};
static struct spi_bus *spi_get_bus(unsigned dev_index)
{
if (dev_index < bus_count)
return &spi_bus[dev_index];
debug("%s: invalid bus %d", __func__, dev_index);
return NULL;
}
static inline struct exynos_spi_slave *to_exynos_spi(struct spi_slave *slave)
{
return container_of(slave, struct exynos_spi_slave, slave);
}
/**
* Setup the driver private data
*
* @param bus ID of the bus that the slave is attached to
* @param cs ID of the chip select connected to the slave
* @param max_hz Required spi frequency
* @param mode Required spi mode (clk polarity, clk phase and
* master or slave)
* @return new device or NULL
*/
struct spi_slave *spi_setup_slave(unsigned int busnum, unsigned int cs,
unsigned int max_hz, unsigned int mode)
{
struct exynos_spi_slave *spi_slave;
struct spi_bus *bus;
if (!spi_cs_is_valid(busnum, cs)) {
debug("%s: Invalid bus/chip select %d, %d\n", __func__,
busnum, cs);
return NULL;
}
spi_slave = spi_alloc_slave(struct exynos_spi_slave, busnum, cs);
if (!spi_slave) {
debug("%s: Could not allocate spi_slave\n", __func__);
return NULL;
}
bus = &spi_bus[busnum];
spi_slave->bus = bus;
spi_slave->regs = bus->regs;
spi_slave->mode = mode;
spi_slave->periph_id = bus->periph_id;
if (bus->periph_id == PERIPH_ID_SPI1 ||
bus->periph_id == PERIPH_ID_SPI2)
spi_slave->fifo_size = 64;
else
spi_slave->fifo_size = 256;
spi_slave->skip_preamble = 0;
spi_slave->last_transaction_us = timer_get_us();
spi_slave->freq = bus->frequency;
if (max_hz)
spi_slave->freq = min(max_hz, spi_slave->freq);
return &spi_slave->slave;
}
/**
* Free spi controller
*
* @param slave Pointer to spi_slave to which controller has to
* communicate with
*/
void spi_free_slave(struct spi_slave *slave)
{
struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
free(spi_slave);
}
/**
* Flush spi tx, rx fifos and reset the SPI controller
*
* @param slave Pointer to spi_slave to which controller has to
* communicate with
*/
static void spi_flush_fifo(struct spi_slave *slave)
{
struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
struct exynos_spi *regs = spi_slave->regs;
clrsetbits_le32(&regs->ch_cfg, SPI_CH_HS_EN, SPI_CH_RST);
clrbits_le32(&regs->ch_cfg, SPI_CH_RST);
setbits_le32(&regs->ch_cfg, SPI_TX_CH_ON | SPI_RX_CH_ON);
}
/**
* Initialize the spi base registers, set the required clock frequency and
* initialize the gpios
*
* @param slave Pointer to spi_slave to which controller has to
* communicate with
* @return zero on success else a negative value
*/
int spi_claim_bus(struct spi_slave *slave)
{
struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
struct exynos_spi *regs = spi_slave->regs;
u32 reg = 0;
int ret;
ret = set_spi_clk(spi_slave->periph_id,
spi_slave->freq);
if (ret < 0) {
debug("%s: Failed to setup spi clock\n", __func__);
return ret;
}
exynos_pinmux_config(spi_slave->periph_id, PINMUX_FLAG_NONE);
spi_flush_fifo(slave);
reg = readl(&regs->ch_cfg);
reg &= ~(SPI_CH_CPHA_B | SPI_CH_CPOL_L);
if (spi_slave->mode & SPI_CPHA)
reg |= SPI_CH_CPHA_B;
if (spi_slave->mode & SPI_CPOL)
reg |= SPI_CH_CPOL_L;
writel(reg, &regs->ch_cfg);
writel(SPI_FB_DELAY_180, &regs->fb_clk);
return 0;
}
/**
* Reset the spi H/W and flush the tx and rx fifos
*
* @param slave Pointer to spi_slave to which controller has to
* communicate with
*/
void spi_release_bus(struct spi_slave *slave)
{
spi_flush_fifo(slave);
}
static void spi_get_fifo_levels(struct exynos_spi *regs,
int *rx_lvl, int *tx_lvl)
{
uint32_t spi_sts = readl(&regs->spi_sts);
*rx_lvl = (spi_sts >> SPI_RX_LVL_OFFSET) & SPI_FIFO_LVL_MASK;
*tx_lvl = (spi_sts >> SPI_TX_LVL_OFFSET) & SPI_FIFO_LVL_MASK;
}
/**
* If there's something to transfer, do a software reset and set a
* transaction size.
*
* @param regs SPI peripheral registers
* @param count Number of bytes to transfer
* @param step Number of bytes to transfer in each packet (1 or 4)
*/
static void spi_request_bytes(struct exynos_spi *regs, int count, int step)
{
/* For word address we need to swap bytes */
if (step == 4) {
setbits_le32(&regs->mode_cfg,
SPI_MODE_CH_WIDTH_WORD | SPI_MODE_BUS_WIDTH_WORD);
count /= 4;
setbits_le32(&regs->swap_cfg, SPI_TX_SWAP_EN | SPI_RX_SWAP_EN |
SPI_TX_BYTE_SWAP | SPI_RX_BYTE_SWAP |
SPI_TX_HWORD_SWAP | SPI_RX_HWORD_SWAP);
} else {
/* Select byte access and clear the swap configuration */
clrbits_le32(&regs->mode_cfg,
SPI_MODE_CH_WIDTH_WORD | SPI_MODE_BUS_WIDTH_WORD);
writel(0, &regs->swap_cfg);
}
assert(count && count < (1 << 16));
setbits_le32(&regs->ch_cfg, SPI_CH_RST);
clrbits_le32(&regs->ch_cfg, SPI_CH_RST);
writel(count | SPI_PACKET_CNT_EN, &regs->pkt_cnt);
}
static int spi_rx_tx(struct exynos_spi_slave *spi_slave, int todo,
void **dinp, void const **doutp, unsigned long flags)
{
struct exynos_spi *regs = spi_slave->regs;
uchar *rxp = *dinp;
const uchar *txp = *doutp;
int rx_lvl, tx_lvl;
uint out_bytes, in_bytes;
int toread;
unsigned start = get_timer(0);
int stopping;
int step;
out_bytes = in_bytes = todo;
stopping = spi_slave->skip_preamble && (flags & SPI_XFER_END) &&
!(spi_slave->mode & SPI_SLAVE);
/*
* Try to transfer words if we can. This helps read performance at
* SPI clock speeds above about 20MHz.
*/
step = 1;
if (!((todo | (uintptr_t)rxp | (uintptr_t)txp) & 3) &&
!spi_slave->skip_preamble)
step = 4;
/*
* If there's something to send, do a software reset and set a
* transaction size.
*/
spi_request_bytes(regs, todo, step);
/*
* Bytes are transmitted/received in pairs. Wait to receive all the
* data because then transmission will be done as well.
*/
toread = in_bytes;
while (in_bytes) {
int temp;
/* Keep the fifos full/empty. */
spi_get_fifo_levels(regs, &rx_lvl, &tx_lvl);
/*
* Don't completely fill the txfifo, since we don't want our
* rxfifo to overflow, and it may already contain data.
*/
while (tx_lvl < spi_slave->fifo_size/2 && out_bytes) {
if (!txp)
temp = -1;
else if (step == 4)
temp = *(uint32_t *)txp;
else
temp = *txp;
writel(temp, &regs->tx_data);
out_bytes -= step;
if (txp)
txp += step;
tx_lvl += step;
}
if (rx_lvl >= step) {
while (rx_lvl >= step) {
temp = readl(&regs->rx_data);
if (spi_slave->skip_preamble) {
if (temp == SPI_PREAMBLE_END_BYTE) {
spi_slave->skip_preamble = 0;
stopping = 0;
}
} else {
if (rxp || stopping) {
*rxp = temp;
rxp += step;
}
in_bytes -= step;
}
toread -= step;
rx_lvl -= step;
}
} else if (!toread) {
/*
* We have run out of input data, but haven't read
* enough bytes after the preamble yet. Read some more,
* and make sure that we transmit dummy bytes too, to
* keep things going.
*/
assert(!out_bytes);
out_bytes = in_bytes;
toread = in_bytes;
txp = NULL;
spi_request_bytes(regs, toread, step);
}
if (spi_slave->skip_preamble && get_timer(start) > 100) {
printf("SPI timeout: in_bytes=%d, out_bytes=%d, ",
in_bytes, out_bytes);
return -1;
}
}
*dinp = rxp;
*doutp = txp;
return 0;
}
/**
* Transfer and receive data
*
* @param slave Pointer to spi_slave to which controller has to
* communicate with
* @param bitlen No of bits to tranfer or receive
* @param dout Pointer to transfer buffer
* @param din Pointer to receive buffer
* @param flags Flags for transfer begin and end
* @return zero on success else a negative value
*/
int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
void *din, unsigned long flags)
{
struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
int upto, todo;
int bytelen;
int ret = 0;
/* spi core configured to do 8 bit transfers */
if (bitlen % 8) {
debug("Non byte aligned SPI transfer.\n");
return -1;
}
/* Start the transaction, if necessary. */
if ((flags & SPI_XFER_BEGIN))
spi_cs_activate(slave);
/*
* Exynos SPI limits each transfer to 65535 transfers. To keep
* things simple, allow a maximum of 65532 bytes. We could allow
* more in word mode, but the performance difference is small.
*/
bytelen = bitlen / 8;
for (upto = 0; !ret && upto < bytelen; upto += todo) {
todo = min(bytelen - upto, (1 << 16) - 4);
ret = spi_rx_tx(spi_slave, todo, &din, &dout, flags);
if (ret)
break;
}
/* Stop the transaction, if necessary. */
if ((flags & SPI_XFER_END) && !(spi_slave->mode & SPI_SLAVE)) {
spi_cs_deactivate(slave);
if (spi_slave->skip_preamble) {
assert(!spi_slave->skip_preamble);
debug("Failed to complete premable transaction\n");
ret = -1;
}
}
return ret;
}
/**
* Validates the bus and chip select numbers
*
* @param bus ID of the bus that the slave is attached to
* @param cs ID of the chip select connected to the slave
* @return one on success else zero
*/
int spi_cs_is_valid(unsigned int bus, unsigned int cs)
{
return spi_get_bus(bus) && cs == 0;
}
/**
* Activate the CS by driving it LOW
*
* @param slave Pointer to spi_slave to which controller has to
* communicate with
*/
void spi_cs_activate(struct spi_slave *slave)
{
struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
/* If it's too soon to do another transaction, wait */
if (spi_slave->bus->deactivate_delay_us &&
spi_slave->last_transaction_us) {
ulong delay_us; /* The delay completed so far */
delay_us = timer_get_us() - spi_slave->last_transaction_us;
if (delay_us < spi_slave->bus->deactivate_delay_us)
udelay(spi_slave->bus->deactivate_delay_us - delay_us);
}
clrbits_le32(&spi_slave->regs->cs_reg, SPI_SLAVE_SIG_INACT);
debug("Activate CS, bus %d\n", spi_slave->slave.bus);
spi_slave->skip_preamble = spi_slave->mode & SPI_PREAMBLE;
/* Remember time of this transaction so we can honour the bus delay */
if (spi_slave->bus->deactivate_delay_us)
spi_slave->last_transaction_us = timer_get_us();
}
/**
* Deactivate the CS by driving it HIGH
*
* @param slave Pointer to spi_slave to which controller has to
* communicate with
*/
void spi_cs_deactivate(struct spi_slave *slave)
{
struct exynos_spi_slave *spi_slave = to_exynos_spi(slave);
setbits_le32(&spi_slave->regs->cs_reg, SPI_SLAVE_SIG_INACT);
debug("Deactivate CS, bus %d\n", spi_slave->slave.bus);
}
static inline struct exynos_spi *get_spi_base(int dev_index)
{
if (dev_index < 3)
return (struct exynos_spi *)samsung_get_base_spi() + dev_index;
else
return (struct exynos_spi *)samsung_get_base_spi_isp() +
(dev_index - 3);
}
/*
* Read the SPI config from the device tree node.
*
* @param blob FDT blob to read from
* @param node Node offset to read from
* @param bus SPI bus structure to fill with information
* @return 0 if ok, or -FDT_ERR_NOTFOUND if something was missing
*/
#ifdef CONFIG_OF_CONTROL
static int spi_get_config(const void *blob, int node, struct spi_bus *bus)
{
bus->node = node;
bus->regs = (struct exynos_spi *)fdtdec_get_addr(blob, node, "reg");
bus->periph_id = pinmux_decode_periph_id(blob, node);
if (bus->periph_id == PERIPH_ID_NONE) {
debug("%s: Invalid peripheral ID %d\n", __func__,
bus->periph_id);
return -FDT_ERR_NOTFOUND;
}
/* Use 500KHz as a suitable default */
bus->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
500000);
bus->deactivate_delay_us = fdtdec_get_int(blob, node,
"spi-deactivate-delay", 0);
return 0;
}
/*
* Process a list of nodes, adding them to our list of SPI ports.
*
* @param blob fdt blob
* @param node_list list of nodes to process (any <=0 are ignored)
* @param count number of nodes to process
* @param is_dvc 1 if these are DVC ports, 0 if standard I2C
* @return 0 if ok, -1 on error
*/
static int process_nodes(const void *blob, int node_list[], int count)
{
int i;
/* build the i2c_controllers[] for each controller */
for (i = 0; i < count; i++) {
int node = node_list[i];
struct spi_bus *bus;
if (node <= 0)
continue;
bus = &spi_bus[i];
if (spi_get_config(blob, node, bus)) {
printf("exynos spi_init: failed to decode bus %d\n",
i);
return -1;
}
debug("spi: controller bus %d at %p, periph_id %d\n",
i, bus->regs, bus->periph_id);
bus->inited = 1;
bus_count++;
}
return 0;
}
#endif
/**
* Set up a new SPI slave for an fdt node
*
* @param blob Device tree blob
* @param node SPI peripheral node to use
* @return 0 if ok, -1 on error
*/
struct spi_slave *spi_setup_slave_fdt(const void *blob, int node,
unsigned int cs, unsigned int max_hz, unsigned int mode)
{
struct spi_bus *bus;
unsigned int i;
for (i = 0, bus = spi_bus; i < bus_count; i++, bus++) {
if (bus->node == node)
return spi_setup_slave(i, cs, max_hz, mode);
}
debug("%s: Failed to find bus node %d\n", __func__, node);
return NULL;
}
/* Sadly there is no error return from this function */
void spi_init(void)
{
int count;
#ifdef CONFIG_OF_CONTROL
int node_list[EXYNOS5_SPI_NUM_CONTROLLERS];
const void *blob = gd->fdt_blob;
count = fdtdec_find_aliases_for_id(blob, "spi",
COMPAT_SAMSUNG_EXYNOS_SPI, node_list,
EXYNOS5_SPI_NUM_CONTROLLERS);
if (process_nodes(blob, node_list, count))
return;
#else
struct spi_bus *bus;
for (count = 0; count < EXYNOS5_SPI_NUM_CONTROLLERS; count++) {
bus = &spi_bus[count];
bus->regs = get_spi_base(count);
bus->periph_id = PERIPH_ID_SPI0 + count;
/* Although Exynos5 supports upto 50Mhz speed,
* we are setting it to 10Mhz for safe side
*/
bus->frequency = 10000000;
bus->inited = 1;
bus->node = 0;
bus_count = EXYNOS5_SPI_NUM_CONTROLLERS;
}
#endif
}