u-boot/drivers/spi/exynos_spi.c

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/*
* (C) Copyright 2012 SAMSUNG Electronics
* Padmavathi Venna <padma.v@samsung.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <dm.h>
#include <errno.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/spi.h>
#include <asm/io.h>
DECLARE_GLOBAL_DATA_PTR;
struct exynos_spi_platdata {
enum periph_id periph_id;
s32 frequency; /* Default clock frequency, -1 for none */
struct exynos_spi *regs;
uint deactivate_delay_us; /* Delay to wait after deactivate */
};
struct exynos_spi_priv {
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;
ulong last_transaction_us; /* Time of last transaction end */
};
/**
* Flush spi tx, rx fifos and reset the SPI controller
*
* @param regs Pointer to SPI registers
*/
static void spi_flush_fifo(struct exynos_spi *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);
}
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)
{
debug("%s: regs=%p, count=%d, step=%d\n", __func__, regs, count, 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_priv *priv, int todo,
void **dinp, void const **doutp, unsigned long flags)
{
struct exynos_spi *regs = priv->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 = priv->skip_preamble && (flags & SPI_XFER_END) &&
!(priv->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) &&
!priv->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 < priv->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 (priv->skip_preamble) {
if (temp == SPI_PREAMBLE_END_BYTE) {
priv->skip_preamble = 0;
stopping = 0;
}
} else {
if (rxp || stopping) {
if (step == 4)
*(uint32_t *)rxp = temp;
else
*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 (priv->skip_preamble && get_timer(start) > 100) {
debug("SPI timeout: in_bytes=%d, out_bytes=%d, ",
in_bytes, out_bytes);
return -ETIMEDOUT;
}
}
*dinp = rxp;
*doutp = txp;
return 0;
}
/**
* Activate the CS by driving it LOW
*
* @param slave Pointer to spi_slave to which controller has to
* communicate with
*/
static void spi_cs_activate(struct udevice *dev)
{
struct udevice *bus = dev->parent;
struct exynos_spi_platdata *pdata = dev_get_platdata(bus);
struct exynos_spi_priv *priv = dev_get_priv(bus);
/* If it's too soon to do another transaction, wait */
if (pdata->deactivate_delay_us &&
priv->last_transaction_us) {
ulong delay_us; /* The delay completed so far */
delay_us = timer_get_us() - priv->last_transaction_us;
if (delay_us < pdata->deactivate_delay_us)
udelay(pdata->deactivate_delay_us - delay_us);
}
clrbits_le32(&priv->regs->cs_reg, SPI_SLAVE_SIG_INACT);
debug("Activate CS, bus '%s'\n", bus->name);
priv->skip_preamble = priv->mode & SPI_PREAMBLE;
}
/**
* Deactivate the CS by driving it HIGH
*
* @param slave Pointer to spi_slave to which controller has to
* communicate with
*/
static void spi_cs_deactivate(struct udevice *dev)
{
struct udevice *bus = dev->parent;
struct exynos_spi_platdata *pdata = dev_get_platdata(bus);
struct exynos_spi_priv *priv = dev_get_priv(bus);
setbits_le32(&priv->regs->cs_reg, SPI_SLAVE_SIG_INACT);
/* Remember time of this transaction so we can honour the bus delay */
if (pdata->deactivate_delay_us)
priv->last_transaction_us = timer_get_us();
debug("Deactivate CS, bus '%s'\n", bus->name);
}
static int exynos_spi_ofdata_to_platdata(struct udevice *bus)
{
struct exynos_spi_platdata *plat = bus->platdata;
const void *blob = gd->fdt_blob;
int node = dev_of_offset(bus);
plat->regs = (struct exynos_spi *)dev_get_addr(bus);
plat->periph_id = pinmux_decode_periph_id(blob, node);
if (plat->periph_id == PERIPH_ID_NONE) {
debug("%s: Invalid peripheral ID %d\n", __func__,
plat->periph_id);
return -FDT_ERR_NOTFOUND;
}
/* Use 500KHz as a suitable default */
plat->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
500000);
plat->deactivate_delay_us = fdtdec_get_int(blob, node,
"spi-deactivate-delay", 0);
debug("%s: regs=%p, periph_id=%d, max-frequency=%d, deactivate_delay=%d\n",
__func__, plat->regs, plat->periph_id, plat->frequency,
plat->deactivate_delay_us);
return 0;
}
static int exynos_spi_probe(struct udevice *bus)
{
struct exynos_spi_platdata *plat = dev_get_platdata(bus);
struct exynos_spi_priv *priv = dev_get_priv(bus);
priv->regs = plat->regs;
if (plat->periph_id == PERIPH_ID_SPI1 ||
plat->periph_id == PERIPH_ID_SPI2)
priv->fifo_size = 64;
else
priv->fifo_size = 256;
priv->skip_preamble = 0;
priv->last_transaction_us = timer_get_us();
priv->freq = plat->frequency;
priv->periph_id = plat->periph_id;
return 0;
}
static int exynos_spi_claim_bus(struct udevice *dev)
{
struct udevice *bus = dev->parent;
struct exynos_spi_priv *priv = dev_get_priv(bus);
exynos_pinmux_config(priv->periph_id, PINMUX_FLAG_NONE);
spi_flush_fifo(priv->regs);
writel(SPI_FB_DELAY_180, &priv->regs->fb_clk);
return 0;
}
static int exynos_spi_release_bus(struct udevice *dev)
{
struct udevice *bus = dev->parent;
struct exynos_spi_priv *priv = dev_get_priv(bus);
spi_flush_fifo(priv->regs);
return 0;
}
static int exynos_spi_xfer(struct udevice *dev, unsigned int bitlen,
const void *dout, void *din, unsigned long flags)
{
struct udevice *bus = dev->parent;
struct exynos_spi_priv *priv = dev_get_priv(bus);
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(dev);
/*
* 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(priv, todo, &din, &dout, flags);
if (ret)
break;
}
/* Stop the transaction, if necessary. */
if ((flags & SPI_XFER_END) && !(priv->mode & SPI_SLAVE)) {
spi_cs_deactivate(dev);
if (priv->skip_preamble) {
assert(!priv->skip_preamble);
debug("Failed to complete premable transaction\n");
ret = -1;
}
}
return ret;
}
static int exynos_spi_set_speed(struct udevice *bus, uint speed)
{
struct exynos_spi_platdata *plat = bus->platdata;
struct exynos_spi_priv *priv = dev_get_priv(bus);
int ret;
if (speed > plat->frequency)
speed = plat->frequency;
ret = set_spi_clk(priv->periph_id, speed);
if (ret)
return ret;
priv->freq = speed;
debug("%s: regs=%p, speed=%d\n", __func__, priv->regs, priv->freq);
return 0;
}
static int exynos_spi_set_mode(struct udevice *bus, uint mode)
{
struct exynos_spi_priv *priv = dev_get_priv(bus);
uint32_t reg;
reg = readl(&priv->regs->ch_cfg);
reg &= ~(SPI_CH_CPHA_B | SPI_CH_CPOL_L);
if (mode & SPI_CPHA)
reg |= SPI_CH_CPHA_B;
if (mode & SPI_CPOL)
reg |= SPI_CH_CPOL_L;
writel(reg, &priv->regs->ch_cfg);
priv->mode = mode;
debug("%s: regs=%p, mode=%d\n", __func__, priv->regs, priv->mode);
return 0;
}
static const struct dm_spi_ops exynos_spi_ops = {
.claim_bus = exynos_spi_claim_bus,
.release_bus = exynos_spi_release_bus,
.xfer = exynos_spi_xfer,
.set_speed = exynos_spi_set_speed,
.set_mode = exynos_spi_set_mode,
/*
* cs_info is not needed, since we require all chip selects to be
* in the device tree explicitly
*/
};
static const struct udevice_id exynos_spi_ids[] = {
{ .compatible = "samsung,exynos-spi" },
{ }
};
U_BOOT_DRIVER(exynos_spi) = {
.name = "exynos_spi",
.id = UCLASS_SPI,
.of_match = exynos_spi_ids,
.ops = &exynos_spi_ops,
.ofdata_to_platdata = exynos_spi_ofdata_to_platdata,
.platdata_auto_alloc_size = sizeof(struct exynos_spi_platdata),
.priv_auto_alloc_size = sizeof(struct exynos_spi_priv),
.probe = exynos_spi_probe,
};