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u-boot-brain/drivers/spi/tegra114_spi.c
Yen Lin 60acde43d7 spi: tegra: clear RDY bit prior to every transfer 
The RDY bit indicates that a transfer is complete. This needs to be
cleared by SW before every single HW transaction, rather than only
at the start of each SW transaction (those being made up of n HW
transactions).

It seems that earlier HW may have cleared this bit autonomously when
starting a new transfer, and hence this code was not needed in practice.
However, this is generally a good idea in all cases. In Tegra124, the
HW behaviour appears to have changed, and SW must explicitly clear this
bit. Otherwise, SW will believe that transfers have completed when they
have not, and may e.g. read stale data from the RX FIFO.

Signed-off-by: Yen Lin <yelin@nvidia.com>
[swarren, rewrote commit description, unified duplicate RDY clearing code
and moved it right before the start of the HW transaction, unconditionally
exit loop after reading RX data, rather than checking if TX FIFO is empty,
since it is guaranteed to be]
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
2013-12-19 00:00:51 +05:30

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/*
* NVIDIA Tegra SPI controller (T114 and later)
*
* Copyright (c) 2010-2013 NVIDIA Corporation
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <common.h>
#include <malloc.h>
#include <asm/io.h>
#include <asm/gpio.h>
#include <asm/arch/clock.h>
#include <asm/arch-tegra/clk_rst.h>
#include <asm/arch-tegra114/tegra114_spi.h>
#include <spi.h>
#include <fdtdec.h>
DECLARE_GLOBAL_DATA_PTR;
/* COMMAND1 */
#define SPI_CMD1_GO (1 << 31)
#define SPI_CMD1_M_S (1 << 30)
#define SPI_CMD1_MODE_MASK 0x3
#define SPI_CMD1_MODE_SHIFT 28
#define SPI_CMD1_CS_SEL_MASK 0x3
#define SPI_CMD1_CS_SEL_SHIFT 26
#define SPI_CMD1_CS_POL_INACTIVE3 (1 << 25)
#define SPI_CMD1_CS_POL_INACTIVE2 (1 << 24)
#define SPI_CMD1_CS_POL_INACTIVE1 (1 << 23)
#define SPI_CMD1_CS_POL_INACTIVE0 (1 << 22)
#define SPI_CMD1_CS_SW_HW (1 << 21)
#define SPI_CMD1_CS_SW_VAL (1 << 20)
#define SPI_CMD1_IDLE_SDA_MASK 0x3
#define SPI_CMD1_IDLE_SDA_SHIFT 18
#define SPI_CMD1_BIDIR (1 << 17)
#define SPI_CMD1_LSBI_FE (1 << 16)
#define SPI_CMD1_LSBY_FE (1 << 15)
#define SPI_CMD1_BOTH_EN_BIT (1 << 14)
#define SPI_CMD1_BOTH_EN_BYTE (1 << 13)
#define SPI_CMD1_RX_EN (1 << 12)
#define SPI_CMD1_TX_EN (1 << 11)
#define SPI_CMD1_PACKED (1 << 5)
#define SPI_CMD1_BIT_LEN_MASK 0x1F
#define SPI_CMD1_BIT_LEN_SHIFT 0
/* COMMAND2 */
#define SPI_CMD2_TX_CLK_TAP_DELAY (1 << 6)
#define SPI_CMD2_TX_CLK_TAP_DELAY_MASK (0x3F << 6)
#define SPI_CMD2_RX_CLK_TAP_DELAY (1 << 0)
#define SPI_CMD2_RX_CLK_TAP_DELAY_MASK (0x3F << 0)
/* TRANSFER STATUS */
#define SPI_XFER_STS_RDY (1 << 30)
/* FIFO STATUS */
#define SPI_FIFO_STS_CS_INACTIVE (1 << 31)
#define SPI_FIFO_STS_FRAME_END (1 << 30)
#define SPI_FIFO_STS_RX_FIFO_FLUSH (1 << 15)
#define SPI_FIFO_STS_TX_FIFO_FLUSH (1 << 14)
#define SPI_FIFO_STS_ERR (1 << 8)
#define SPI_FIFO_STS_TX_FIFO_OVF (1 << 7)
#define SPI_FIFO_STS_TX_FIFO_UNR (1 << 6)
#define SPI_FIFO_STS_RX_FIFO_OVF (1 << 5)
#define SPI_FIFO_STS_RX_FIFO_UNR (1 << 4)
#define SPI_FIFO_STS_TX_FIFO_FULL (1 << 3)
#define SPI_FIFO_STS_TX_FIFO_EMPTY (1 << 2)
#define SPI_FIFO_STS_RX_FIFO_FULL (1 << 1)
#define SPI_FIFO_STS_RX_FIFO_EMPTY (1 << 0)
#define SPI_TIMEOUT 1000
#define TEGRA_SPI_MAX_FREQ 52000000
struct spi_regs {
u32 command1; /* 000:SPI_COMMAND1 register */
u32 command2; /* 004:SPI_COMMAND2 register */
u32 timing1; /* 008:SPI_CS_TIM1 register */
u32 timing2; /* 00c:SPI_CS_TIM2 register */
u32 xfer_status;/* 010:SPI_TRANS_STATUS register */
u32 fifo_status;/* 014:SPI_FIFO_STATUS register */
u32 tx_data; /* 018:SPI_TX_DATA register */
u32 rx_data; /* 01c:SPI_RX_DATA register */
u32 dma_ctl; /* 020:SPI_DMA_CTL register */
u32 dma_blk; /* 024:SPI_DMA_BLK register */
u32 rsvd[56]; /* 028-107 reserved */
u32 tx_fifo; /* 108:SPI_FIFO1 register */
u32 rsvd2[31]; /* 10c-187 reserved */
u32 rx_fifo; /* 188:SPI_FIFO2 register */
u32 spare_ctl; /* 18c:SPI_SPARE_CTRL register */
};
struct tegra_spi_ctrl {
struct spi_regs *regs;
unsigned int freq;
unsigned int mode;
int periph_id;
int valid;
};
struct tegra_spi_slave {
struct spi_slave slave;
struct tegra_spi_ctrl *ctrl;
};
static struct tegra_spi_ctrl spi_ctrls[CONFIG_TEGRA114_SPI_CTRLS];
static inline struct tegra_spi_slave *to_tegra_spi(struct spi_slave *slave)
{
return container_of(slave, struct tegra_spi_slave, slave);
}
int tegra114_spi_cs_is_valid(unsigned int bus, unsigned int cs)
{
if (bus >= CONFIG_TEGRA114_SPI_CTRLS || cs > 3 || !spi_ctrls[bus].valid)
return 0;
else
return 1;
}
struct spi_slave *tegra114_spi_setup_slave(unsigned int bus, unsigned int cs,
unsigned int max_hz, unsigned int mode)
{
struct tegra_spi_slave *spi;
debug("%s: bus: %u, cs: %u, max_hz: %u, mode: %u\n", __func__,
bus, cs, max_hz, mode);
if (!spi_cs_is_valid(bus, cs)) {
printf("SPI error: unsupported bus %d / chip select %d\n",
bus, cs);
return NULL;
}
if (max_hz > TEGRA_SPI_MAX_FREQ) {
printf("SPI error: unsupported frequency %d Hz. Max frequency"
" is %d Hz\n", max_hz, TEGRA_SPI_MAX_FREQ);
return NULL;
}
spi = spi_alloc_slave(struct tegra_spi_slave, bus, cs);
if (!spi) {
printf("SPI error: malloc of SPI structure failed\n");
return NULL;
}
spi->ctrl = &spi_ctrls[bus];
if (!spi->ctrl) {
printf("SPI error: could not find controller for bus %d\n",
bus);
return NULL;
}
if (max_hz < spi->ctrl->freq) {
debug("%s: limiting frequency from %u to %u\n", __func__,
spi->ctrl->freq, max_hz);
spi->ctrl->freq = max_hz;
}
spi->ctrl->mode = mode;
return &spi->slave;
}
void tegra114_spi_free_slave(struct spi_slave *slave)
{
struct tegra_spi_slave *spi = to_tegra_spi(slave);
free(spi);
}
int tegra114_spi_init(int *node_list, int count)
{
struct tegra_spi_ctrl *ctrl;
int i;
int node = 0;
int found = 0;
for (i = 0; i < count; i++) {
ctrl = &spi_ctrls[i];
node = node_list[i];
ctrl->regs = (struct spi_regs *)fdtdec_get_addr(gd->fdt_blob,
node, "reg");
if ((fdt_addr_t)ctrl->regs == FDT_ADDR_T_NONE) {
debug("%s: no spi register found\n", __func__);
continue;
}
ctrl->freq = fdtdec_get_int(gd->fdt_blob, node,
"spi-max-frequency", 0);
if (!ctrl->freq) {
debug("%s: no spi max frequency found\n", __func__);
continue;
}
ctrl->periph_id = clock_decode_periph_id(gd->fdt_blob, node);
if (ctrl->periph_id == PERIPH_ID_NONE) {
debug("%s: could not decode periph id\n", __func__);
continue;
}
ctrl->valid = 1;
found = 1;
debug("%s: found controller at %p, freq = %u, periph_id = %d\n",
__func__, ctrl->regs, ctrl->freq, ctrl->periph_id);
}
return !found;
}
int tegra114_spi_claim_bus(struct spi_slave *slave)
{
struct tegra_spi_slave *spi = to_tegra_spi(slave);
struct spi_regs *regs = spi->ctrl->regs;
/* Change SPI clock to correct frequency, PLLP_OUT0 source */
clock_start_periph_pll(spi->ctrl->periph_id, CLOCK_ID_PERIPH,
spi->ctrl->freq);
/* Clear stale status here */
setbits_le32(&regs->fifo_status,
SPI_FIFO_STS_ERR |
SPI_FIFO_STS_TX_FIFO_OVF |
SPI_FIFO_STS_TX_FIFO_UNR |
SPI_FIFO_STS_RX_FIFO_OVF |
SPI_FIFO_STS_RX_FIFO_UNR |
SPI_FIFO_STS_TX_FIFO_FULL |
SPI_FIFO_STS_TX_FIFO_EMPTY |
SPI_FIFO_STS_RX_FIFO_FULL |
SPI_FIFO_STS_RX_FIFO_EMPTY);
debug("%s: FIFO STATUS = %08x\n", __func__, readl(&regs->fifo_status));
/* Set master mode and sw controlled CS */
setbits_le32(&regs->command1, SPI_CMD1_M_S | SPI_CMD1_CS_SW_HW |
(spi->ctrl->mode << SPI_CMD1_MODE_SHIFT));
debug("%s: COMMAND1 = %08x\n", __func__, readl(&regs->command1));
return 0;
}
void tegra114_spi_cs_activate(struct spi_slave *slave)
{
struct tegra_spi_slave *spi = to_tegra_spi(slave);
struct spi_regs *regs = spi->ctrl->regs;
clrbits_le32(&regs->command1, SPI_CMD1_CS_SW_VAL);
}
void tegra114_spi_cs_deactivate(struct spi_slave *slave)
{
struct tegra_spi_slave *spi = to_tegra_spi(slave);
struct spi_regs *regs = spi->ctrl->regs;
setbits_le32(&regs->command1, SPI_CMD1_CS_SW_VAL);
}
int tegra114_spi_xfer(struct spi_slave *slave, unsigned int bitlen,
const void *data_out, void *data_in, unsigned long flags)
{
struct tegra_spi_slave *spi = to_tegra_spi(slave);
struct spi_regs *regs = spi->ctrl->regs;
u32 reg, tmpdout, tmpdin = 0;
const u8 *dout = data_out;
u8 *din = data_in;
int num_bytes;
int ret;
debug("%s: slave %u:%u dout %p din %p bitlen %u\n",
__func__, slave->bus, slave->cs, dout, din, bitlen);
if (bitlen % 8)
return -1;
num_bytes = bitlen / 8;
ret = 0;
/* clear all error status bits */
reg = readl(&regs->fifo_status);
writel(reg, &regs->fifo_status);
clrsetbits_le32(&regs->command1, SPI_CMD1_CS_SW_VAL,
SPI_CMD1_RX_EN | SPI_CMD1_TX_EN | SPI_CMD1_LSBY_FE |
(slave->cs << SPI_CMD1_CS_SEL_SHIFT));
/* set xfer size to 1 block (32 bits) */
writel(0, &regs->dma_blk);
if (flags & SPI_XFER_BEGIN)
spi_cs_activate(slave);
/* handle data in 32-bit chunks */
while (num_bytes > 0) {
int bytes;
int tm, i;
tmpdout = 0;
bytes = (num_bytes > 4) ? 4 : num_bytes;
if (dout != NULL) {
for (i = 0; i < bytes; ++i)
tmpdout = (tmpdout << 8) | dout[i];
dout += bytes;
}
num_bytes -= bytes;
/* clear ready bit */
setbits_le32(&regs->xfer_status, SPI_XFER_STS_RDY);
clrsetbits_le32(&regs->command1,
SPI_CMD1_BIT_LEN_MASK << SPI_CMD1_BIT_LEN_SHIFT,
(bytes * 8 - 1) << SPI_CMD1_BIT_LEN_SHIFT);
writel(tmpdout, &regs->tx_fifo);
setbits_le32(&regs->command1, SPI_CMD1_GO);
/*
* Wait for SPI transmit FIFO to empty, or to time out.
* The RX FIFO status will be read and cleared last
*/
for (tm = 0; tm < SPI_TIMEOUT; ++tm) {
u32 fifo_status, xfer_status;
xfer_status = readl(&regs->xfer_status);
if (!(xfer_status & SPI_XFER_STS_RDY))
continue;
fifo_status = readl(&regs->fifo_status);
if (fifo_status & SPI_FIFO_STS_ERR) {
debug("%s: got a fifo error: ", __func__);
if (fifo_status & SPI_FIFO_STS_TX_FIFO_OVF)
debug("tx FIFO overflow ");
if (fifo_status & SPI_FIFO_STS_TX_FIFO_UNR)
debug("tx FIFO underrun ");
if (fifo_status & SPI_FIFO_STS_RX_FIFO_OVF)
debug("rx FIFO overflow ");
if (fifo_status & SPI_FIFO_STS_RX_FIFO_UNR)
debug("rx FIFO underrun ");
if (fifo_status & SPI_FIFO_STS_TX_FIFO_FULL)
debug("tx FIFO full ");
if (fifo_status & SPI_FIFO_STS_TX_FIFO_EMPTY)
debug("tx FIFO empty ");
if (fifo_status & SPI_FIFO_STS_RX_FIFO_FULL)
debug("rx FIFO full ");
if (fifo_status & SPI_FIFO_STS_RX_FIFO_EMPTY)
debug("rx FIFO empty ");
debug("\n");
break;
}
if (!(fifo_status & SPI_FIFO_STS_RX_FIFO_EMPTY)) {
tmpdin = readl(&regs->rx_fifo);
/* swap bytes read in */
if (din != NULL) {
for (i = bytes - 1; i >= 0; --i) {
din[i] = tmpdin & 0xff;
tmpdin >>= 8;
}
din += bytes;
}
/* We can exit when we've had both RX and TX */
break;
}
}
if (tm >= SPI_TIMEOUT)
ret = tm;
/* clear ACK RDY, etc. bits */
writel(readl(&regs->fifo_status), &regs->fifo_status);
}
if (flags & SPI_XFER_END)
spi_cs_deactivate(slave);
debug("%s: transfer ended. Value=%08x, fifo_status = %08x\n",
__func__, tmpdin, readl(&regs->fifo_status));
if (ret) {
printf("%s: timeout during SPI transfer, tm %d\n",
__func__, ret);
return -1;
}
return 0;
}
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