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linux/drivers/spi/spi-davinci.c
Murali Karicheri 32310aaf5c spi/davinci: use request_threaded_irq() to fix deadlock 
With RT pre-empt patch applied to Linux kernel, the irq handler will be
force converted to an irq thread. spi driver can get back to back messages
from the slave device. In such cases, IRQ thread doesn't get a chance to
run to read the slave data. Hence the irq handler must be run in hard irq
context to read/write data from slave device. Otherwise, the kernel goes
into a deadlock. This patch fixes this issue when PREEMPT_RT_FULL is
enabled in the kernel. A dummy thread function is provided to satisfy the
request_threaded_irq() API. Passing a NULL for function also causes the
irq handler to be executed in the thread context.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2013-02-05 17:12:26 +00:00

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/*
* Copyright (C) 2009 Texas Instruments.
* Copyright (C) 2010 EF Johnson Technologies
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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 <linux/interrupt.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/edma.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/slab.h>
#include <linux/platform_data/spi-davinci.h>
#define SPI_NO_RESOURCE ((resource_size_t)-1)
#define SPI_MAX_CHIPSELECT 2
#define CS_DEFAULT 0xFF
#define SPIFMT_PHASE_MASK BIT(16)
#define SPIFMT_POLARITY_MASK BIT(17)
#define SPIFMT_DISTIMER_MASK BIT(18)
#define SPIFMT_SHIFTDIR_MASK BIT(20)
#define SPIFMT_WAITENA_MASK BIT(21)
#define SPIFMT_PARITYENA_MASK BIT(22)
#define SPIFMT_ODD_PARITY_MASK BIT(23)
#define SPIFMT_WDELAY_MASK 0x3f000000u
#define SPIFMT_WDELAY_SHIFT 24
#define SPIFMT_PRESCALE_SHIFT 8
/* SPIPC0 */
#define SPIPC0_DIFUN_MASK BIT(11) /* MISO */
#define SPIPC0_DOFUN_MASK BIT(10) /* MOSI */
#define SPIPC0_CLKFUN_MASK BIT(9) /* CLK */
#define SPIPC0_SPIENA_MASK BIT(8) /* nREADY */
#define SPIINT_MASKALL 0x0101035F
#define SPIINT_MASKINT 0x0000015F
#define SPI_INTLVL_1 0x000001FF
#define SPI_INTLVL_0 0x00000000
/* SPIDAT1 (upper 16 bit defines) */
#define SPIDAT1_CSHOLD_MASK BIT(12)
/* SPIGCR1 */
#define SPIGCR1_CLKMOD_MASK BIT(1)
#define SPIGCR1_MASTER_MASK BIT(0)
#define SPIGCR1_POWERDOWN_MASK BIT(8)
#define SPIGCR1_LOOPBACK_MASK BIT(16)
#define SPIGCR1_SPIENA_MASK BIT(24)
/* SPIBUF */
#define SPIBUF_TXFULL_MASK BIT(29)
#define SPIBUF_RXEMPTY_MASK BIT(31)
/* SPIDELAY */
#define SPIDELAY_C2TDELAY_SHIFT 24
#define SPIDELAY_C2TDELAY_MASK (0xFF << SPIDELAY_C2TDELAY_SHIFT)
#define SPIDELAY_T2CDELAY_SHIFT 16
#define SPIDELAY_T2CDELAY_MASK (0xFF << SPIDELAY_T2CDELAY_SHIFT)
#define SPIDELAY_T2EDELAY_SHIFT 8
#define SPIDELAY_T2EDELAY_MASK (0xFF << SPIDELAY_T2EDELAY_SHIFT)
#define SPIDELAY_C2EDELAY_SHIFT 0
#define SPIDELAY_C2EDELAY_MASK 0xFF
/* Error Masks */
#define SPIFLG_DLEN_ERR_MASK BIT(0)
#define SPIFLG_TIMEOUT_MASK BIT(1)
#define SPIFLG_PARERR_MASK BIT(2)
#define SPIFLG_DESYNC_MASK BIT(3)
#define SPIFLG_BITERR_MASK BIT(4)
#define SPIFLG_OVRRUN_MASK BIT(6)
#define SPIFLG_BUF_INIT_ACTIVE_MASK BIT(24)
#define SPIFLG_ERROR_MASK (SPIFLG_DLEN_ERR_MASK \
| SPIFLG_TIMEOUT_MASK | SPIFLG_PARERR_MASK \
| SPIFLG_DESYNC_MASK | SPIFLG_BITERR_MASK \
| SPIFLG_OVRRUN_MASK)
#define SPIINT_DMA_REQ_EN BIT(16)
/* SPI Controller registers */
#define SPIGCR0 0x00
#define SPIGCR1 0x04
#define SPIINT 0x08
#define SPILVL 0x0c
#define SPIFLG 0x10
#define SPIPC0 0x14
#define SPIDAT1 0x3c
#define SPIBUF 0x40
#define SPIDELAY 0x48
#define SPIDEF 0x4c
#define SPIFMT0 0x50
/* SPI Controller driver's private data. */
struct davinci_spi {
struct spi_bitbang bitbang;
struct clk *clk;
u8 version;
resource_size_t pbase;
void __iomem *base;
u32 irq;
struct completion done;
const void *tx;
void *rx;
int rcount;
int wcount;
struct dma_chan *dma_rx;
struct dma_chan *dma_tx;
int dma_rx_chnum;
int dma_tx_chnum;
struct davinci_spi_platform_data pdata;
void (*get_rx)(u32 rx_data, struct davinci_spi *);
u32 (*get_tx)(struct davinci_spi *);
u8 bytes_per_word[SPI_MAX_CHIPSELECT];
};
static struct davinci_spi_config davinci_spi_default_cfg;
static void davinci_spi_rx_buf_u8(u32 data, struct davinci_spi *dspi)
{
if (dspi->rx) {
u8 *rx = dspi->rx;
*rx++ = (u8)data;
dspi->rx = rx;
}
}
static void davinci_spi_rx_buf_u16(u32 data, struct davinci_spi *dspi)
{
if (dspi->rx) {
u16 *rx = dspi->rx;
*rx++ = (u16)data;
dspi->rx = rx;
}
}
static u32 davinci_spi_tx_buf_u8(struct davinci_spi *dspi)
{
u32 data = 0;
if (dspi->tx) {
const u8 *tx = dspi->tx;
data = *tx++;
dspi->tx = tx;
}
return data;
}
static u32 davinci_spi_tx_buf_u16(struct davinci_spi *dspi)
{
u32 data = 0;
if (dspi->tx) {
const u16 *tx = dspi->tx;
data = *tx++;
dspi->tx = tx;
}
return data;
}
static inline void set_io_bits(void __iomem *addr, u32 bits)
{
u32 v = ioread32(addr);
v |= bits;
iowrite32(v, addr);
}
static inline void clear_io_bits(void __iomem *addr, u32 bits)
{
u32 v = ioread32(addr);
v &= ~bits;
iowrite32(v, addr);
}
/*
* Interface to control the chip select signal
*/
static void davinci_spi_chipselect(struct spi_device *spi, int value)
{
struct davinci_spi *dspi;
struct davinci_spi_platform_data *pdata;
u8 chip_sel = spi->chip_select;
u16 spidat1 = CS_DEFAULT;
bool gpio_chipsel = false;
dspi = spi_master_get_devdata(spi->master);
pdata = &dspi->pdata;
if (pdata->chip_sel && chip_sel < pdata->num_chipselect &&
pdata->chip_sel[chip_sel] != SPI_INTERN_CS)
gpio_chipsel = true;
/*
* Board specific chip select logic decides the polarity and cs
* line for the controller
*/
if (gpio_chipsel) {
if (value == BITBANG_CS_ACTIVE)
gpio_set_value(pdata->chip_sel[chip_sel], 0);
else
gpio_set_value(pdata->chip_sel[chip_sel], 1);
} else {
if (value == BITBANG_CS_ACTIVE) {
spidat1 |= SPIDAT1_CSHOLD_MASK;
spidat1 &= ~(0x1 << chip_sel);
}
iowrite16(spidat1, dspi->base + SPIDAT1 + 2);
}
}
/**
* davinci_spi_get_prescale - Calculates the correct prescale value
* @maxspeed_hz: the maximum rate the SPI clock can run at
*
* This function calculates the prescale value that generates a clock rate
* less than or equal to the specified maximum.
*
* Returns: calculated prescale - 1 for easy programming into SPI registers
* or negative error number if valid prescalar cannot be updated.
*/
static inline int davinci_spi_get_prescale(struct davinci_spi *dspi,
u32 max_speed_hz)
{
int ret;
ret = DIV_ROUND_UP(clk_get_rate(dspi->clk), max_speed_hz);
if (ret < 3 || ret > 256)
return -EINVAL;
return ret - 1;
}
/**
* davinci_spi_setup_transfer - This functions will determine transfer method
* @spi: spi device on which data transfer to be done
* @t: spi transfer in which transfer info is filled
*
* This function determines data transfer method (8/16/32 bit transfer).
* It will also set the SPI Clock Control register according to
* SPI slave device freq.
*/
static int davinci_spi_setup_transfer(struct spi_device *spi,
struct spi_transfer *t)
{
struct davinci_spi *dspi;
struct davinci_spi_config *spicfg;
u8 bits_per_word = 0;
u32 hz = 0, spifmt = 0, prescale = 0;
dspi = spi_master_get_devdata(spi->master);
spicfg = (struct davinci_spi_config *)spi->controller_data;
if (!spicfg)
spicfg = &davinci_spi_default_cfg;
if (t) {
bits_per_word = t->bits_per_word;
hz = t->speed_hz;
}
/* if bits_per_word is not set then set it default */
if (!bits_per_word)
bits_per_word = spi->bits_per_word;
/*
* Assign function pointer to appropriate transfer method
* 8bit, 16bit or 32bit transfer
*/
if (bits_per_word <= 8 && bits_per_word >= 2) {
dspi->get_rx = davinci_spi_rx_buf_u8;
dspi->get_tx = davinci_spi_tx_buf_u8;
dspi->bytes_per_word[spi->chip_select] = 1;
} else if (bits_per_word <= 16 && bits_per_word >= 2) {
dspi->get_rx = davinci_spi_rx_buf_u16;
dspi->get_tx = davinci_spi_tx_buf_u16;
dspi->bytes_per_word[spi->chip_select] = 2;
} else
return -EINVAL;
if (!hz)
hz = spi->max_speed_hz;
/* Set up SPIFMTn register, unique to this chipselect. */
prescale = davinci_spi_get_prescale(dspi, hz);
if (prescale < 0)
return prescale;
spifmt = (prescale << SPIFMT_PRESCALE_SHIFT) | (bits_per_word & 0x1f);
if (spi->mode & SPI_LSB_FIRST)
spifmt |= SPIFMT_SHIFTDIR_MASK;
if (spi->mode & SPI_CPOL)
spifmt |= SPIFMT_POLARITY_MASK;
if (!(spi->mode & SPI_CPHA))
spifmt |= SPIFMT_PHASE_MASK;
/*
* Version 1 hardware supports two basic SPI modes:
* - Standard SPI mode uses 4 pins, with chipselect
* - 3 pin SPI is a 4 pin variant without CS (SPI_NO_CS)
* (distinct from SPI_3WIRE, with just one data wire;
* or similar variants without MOSI or without MISO)
*
* Version 2 hardware supports an optional handshaking signal,
* so it can support two more modes:
* - 5 pin SPI variant is standard SPI plus SPI_READY
* - 4 pin with enable is (SPI_READY | SPI_NO_CS)
*/
if (dspi->version == SPI_VERSION_2) {
u32 delay = 0;
spifmt |= ((spicfg->wdelay << SPIFMT_WDELAY_SHIFT)
& SPIFMT_WDELAY_MASK);
if (spicfg->odd_parity)
spifmt |= SPIFMT_ODD_PARITY_MASK;
if (spicfg->parity_enable)
spifmt |= SPIFMT_PARITYENA_MASK;
if (spicfg->timer_disable) {
spifmt |= SPIFMT_DISTIMER_MASK;
} else {
delay |= (spicfg->c2tdelay << SPIDELAY_C2TDELAY_SHIFT)
& SPIDELAY_C2TDELAY_MASK;
delay |= (spicfg->t2cdelay << SPIDELAY_T2CDELAY_SHIFT)
& SPIDELAY_T2CDELAY_MASK;
}
if (spi->mode & SPI_READY) {
spifmt |= SPIFMT_WAITENA_MASK;
delay |= (spicfg->t2edelay << SPIDELAY_T2EDELAY_SHIFT)
& SPIDELAY_T2EDELAY_MASK;
delay |= (spicfg->c2edelay << SPIDELAY_C2EDELAY_SHIFT)
& SPIDELAY_C2EDELAY_MASK;
}
iowrite32(delay, dspi->base + SPIDELAY);
}
iowrite32(spifmt, dspi->base + SPIFMT0);
return 0;
}
/**
* davinci_spi_setup - This functions will set default transfer method
* @spi: spi device on which data transfer to be done
*
* This functions sets the default transfer method.
*/
static int davinci_spi_setup(struct spi_device *spi)
{
int retval = 0;
struct davinci_spi *dspi;
struct davinci_spi_platform_data *pdata;
dspi = spi_master_get_devdata(spi->master);
pdata = &dspi->pdata;
/* if bits per word length is zero then set it default 8 */
if (!spi->bits_per_word)
spi->bits_per_word = 8;
if (!(spi->mode & SPI_NO_CS)) {
if ((pdata->chip_sel == NULL) ||
(pdata->chip_sel[spi->chip_select] == SPI_INTERN_CS))
set_io_bits(dspi->base + SPIPC0, 1 << spi->chip_select);
}
if (spi->mode & SPI_READY)
set_io_bits(dspi->base + SPIPC0, SPIPC0_SPIENA_MASK);
if (spi->mode & SPI_LOOP)
set_io_bits(dspi->base + SPIGCR1, SPIGCR1_LOOPBACK_MASK);
else
clear_io_bits(dspi->base + SPIGCR1, SPIGCR1_LOOPBACK_MASK);
return retval;
}
static int davinci_spi_check_error(struct davinci_spi *dspi, int int_status)
{
struct device *sdev = dspi->bitbang.master->dev.parent;
if (int_status & SPIFLG_TIMEOUT_MASK) {
dev_dbg(sdev, "SPI Time-out Error\n");
return -ETIMEDOUT;
}
if (int_status & SPIFLG_DESYNC_MASK) {
dev_dbg(sdev, "SPI Desynchronization Error\n");
return -EIO;
}
if (int_status & SPIFLG_BITERR_MASK) {
dev_dbg(sdev, "SPI Bit error\n");
return -EIO;
}
if (dspi->version == SPI_VERSION_2) {
if (int_status & SPIFLG_DLEN_ERR_MASK) {
dev_dbg(sdev, "SPI Data Length Error\n");
return -EIO;
}
if (int_status & SPIFLG_PARERR_MASK) {
dev_dbg(sdev, "SPI Parity Error\n");
return -EIO;
}
if (int_status & SPIFLG_OVRRUN_MASK) {
dev_dbg(sdev, "SPI Data Overrun error\n");
return -EIO;
}
if (int_status & SPIFLG_BUF_INIT_ACTIVE_MASK) {
dev_dbg(sdev, "SPI Buffer Init Active\n");
return -EBUSY;
}
}
return 0;
}
/**
* davinci_spi_process_events - check for and handle any SPI controller events
* @dspi: the controller data
*
* This function will check the SPIFLG register and handle any events that are
* detected there
*/
static int davinci_spi_process_events(struct davinci_spi *dspi)
{
u32 buf, status, errors = 0, spidat1;
buf = ioread32(dspi->base + SPIBUF);
if (dspi->rcount > 0 && !(buf & SPIBUF_RXEMPTY_MASK)) {
dspi->get_rx(buf & 0xFFFF, dspi);
dspi->rcount--;
}
status = ioread32(dspi->base + SPIFLG);
if (unlikely(status & SPIFLG_ERROR_MASK)) {
errors = status & SPIFLG_ERROR_MASK;
goto out;
}
if (dspi->wcount > 0 && !(buf & SPIBUF_TXFULL_MASK)) {
spidat1 = ioread32(dspi->base + SPIDAT1);
dspi->wcount--;
spidat1 &= ~0xFFFF;
spidat1 |= 0xFFFF & dspi->get_tx(dspi);
iowrite32(spidat1, dspi->base + SPIDAT1);
}
out:
return errors;
}
static void davinci_spi_dma_rx_callback(void *data)
{
struct davinci_spi *dspi = (struct davinci_spi *)data;
dspi->rcount = 0;
if (!dspi->wcount && !dspi->rcount)
complete(&dspi->done);
}
static void davinci_spi_dma_tx_callback(void *data)
{
struct davinci_spi *dspi = (struct davinci_spi *)data;
dspi->wcount = 0;
if (!dspi->wcount && !dspi->rcount)
complete(&dspi->done);
}
/**
* davinci_spi_bufs - functions which will handle transfer data
* @spi: spi device on which data transfer to be done
* @t: spi transfer in which transfer info is filled
*
* This function will put data to be transferred into data register
* of SPI controller and then wait until the completion will be marked
* by the IRQ Handler.
*/
static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t)
{
struct davinci_spi *dspi;
int data_type, ret = -ENOMEM;
u32 tx_data, spidat1;
u32 errors = 0;
struct davinci_spi_config *spicfg;
struct davinci_spi_platform_data *pdata;
unsigned uninitialized_var(rx_buf_count);
void *dummy_buf = NULL;
struct scatterlist sg_rx, sg_tx;
dspi = spi_master_get_devdata(spi->master);
pdata = &dspi->pdata;
spicfg = (struct davinci_spi_config *)spi->controller_data;
if (!spicfg)
spicfg = &davinci_spi_default_cfg;
/* convert len to words based on bits_per_word */
data_type = dspi->bytes_per_word[spi->chip_select];
dspi->tx = t->tx_buf;
dspi->rx = t->rx_buf;
dspi->wcount = t->len / data_type;
dspi->rcount = dspi->wcount;
spidat1 = ioread32(dspi->base + SPIDAT1);
clear_io_bits(dspi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK);
set_io_bits(dspi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
INIT_COMPLETION(dspi->done);
if (spicfg->io_type == SPI_IO_TYPE_INTR)
set_io_bits(dspi->base + SPIINT, SPIINT_MASKINT);
if (spicfg->io_type != SPI_IO_TYPE_DMA) {
/* start the transfer */
dspi->wcount--;
tx_data = dspi->get_tx(dspi);
spidat1 &= 0xFFFF0000;
spidat1 |= tx_data & 0xFFFF;
iowrite32(spidat1, dspi->base + SPIDAT1);
} else {
struct dma_slave_config dma_rx_conf = {
.direction = DMA_DEV_TO_MEM,
.src_addr = (unsigned long)dspi->pbase + SPIBUF,
.src_addr_width = data_type,
.src_maxburst = 1,
};
struct dma_slave_config dma_tx_conf = {
.direction = DMA_MEM_TO_DEV,
.dst_addr = (unsigned long)dspi->pbase + SPIDAT1,
.dst_addr_width = data_type,
.dst_maxburst = 1,
};
struct dma_async_tx_descriptor *rxdesc;
struct dma_async_tx_descriptor *txdesc;
void *buf;
dummy_buf = kzalloc(t->len, GFP_KERNEL);
if (!dummy_buf)
goto err_alloc_dummy_buf;
dmaengine_slave_config(dspi->dma_rx, &dma_rx_conf);
dmaengine_slave_config(dspi->dma_tx, &dma_tx_conf);
sg_init_table(&sg_rx, 1);
if (!t->rx_buf)
buf = dummy_buf;
else
buf = t->rx_buf;
t->rx_dma = dma_map_single(&spi->dev, buf,
t->len, DMA_FROM_DEVICE);
if (!t->rx_dma) {
ret = -EFAULT;
goto err_rx_map;
}
sg_dma_address(&sg_rx) = t->rx_dma;
sg_dma_len(&sg_rx) = t->len;
sg_init_table(&sg_tx, 1);
if (!t->tx_buf)
buf = dummy_buf;
else
buf = (void *)t->tx_buf;
t->tx_dma = dma_map_single(&spi->dev, buf,
t->len, DMA_FROM_DEVICE);
if (!t->tx_dma) {
ret = -EFAULT;
goto err_tx_map;
}
sg_dma_address(&sg_tx) = t->tx_dma;
sg_dma_len(&sg_tx) = t->len;
rxdesc = dmaengine_prep_slave_sg(dspi->dma_rx,
&sg_rx, 1, DMA_DEV_TO_MEM,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!rxdesc)
goto err_desc;
txdesc = dmaengine_prep_slave_sg(dspi->dma_tx,
&sg_tx, 1, DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!txdesc)
goto err_desc;
rxdesc->callback = davinci_spi_dma_rx_callback;
rxdesc->callback_param = (void *)dspi;
txdesc->callback = davinci_spi_dma_tx_callback;
txdesc->callback_param = (void *)dspi;
if (pdata->cshold_bug)
iowrite16(spidat1 >> 16, dspi->base + SPIDAT1 + 2);
dmaengine_submit(rxdesc);
dmaengine_submit(txdesc);
dma_async_issue_pending(dspi->dma_rx);
dma_async_issue_pending(dspi->dma_tx);
set_io_bits(dspi->base + SPIINT, SPIINT_DMA_REQ_EN);
}
/* Wait for the transfer to complete */
if (spicfg->io_type != SPI_IO_TYPE_POLL) {
wait_for_completion_interruptible(&(dspi->done));
} else {
while (dspi->rcount > 0 || dspi->wcount > 0) {
errors = davinci_spi_process_events(dspi);
if (errors)
break;
cpu_relax();
}
}
clear_io_bits(dspi->base + SPIINT, SPIINT_MASKALL);
if (spicfg->io_type == SPI_IO_TYPE_DMA) {
clear_io_bits(dspi->base + SPIINT, SPIINT_DMA_REQ_EN);
dma_unmap_single(&spi->dev, t->rx_dma,
t->len, DMA_FROM_DEVICE);
dma_unmap_single(&spi->dev, t->tx_dma,
t->len, DMA_TO_DEVICE);
kfree(dummy_buf);
}
clear_io_bits(dspi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
set_io_bits(dspi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK);
/*
* Check for bit error, desync error,parity error,timeout error and
* receive overflow errors
*/
if (errors) {
ret = davinci_spi_check_error(dspi, errors);
WARN(!ret, "%s: error reported but no error found!\n",
dev_name(&spi->dev));
return ret;
}
if (dspi->rcount != 0 || dspi->wcount != 0) {
dev_err(&spi->dev, "SPI data transfer error\n");
return -EIO;
}
return t->len;
err_desc:
dma_unmap_single(&spi->dev, t->tx_dma, t->len, DMA_TO_DEVICE);
err_tx_map:
dma_unmap_single(&spi->dev, t->rx_dma, t->len, DMA_FROM_DEVICE);
err_rx_map:
kfree(dummy_buf);
err_alloc_dummy_buf:
return ret;
}
/**
* dummy_thread_fn - dummy thread function
* @irq: IRQ number for this SPI Master
* @context_data: structure for SPI Master controller davinci_spi
*
* This is to satisfy the request_threaded_irq() API so that the irq
* handler is called in interrupt context.
*/
static irqreturn_t dummy_thread_fn(s32 irq, void *data)
{
return IRQ_HANDLED;
}
/**
* davinci_spi_irq - Interrupt handler for SPI Master Controller
* @irq: IRQ number for this SPI Master
* @context_data: structure for SPI Master controller davinci_spi
*
* ISR will determine that interrupt arrives either for READ or WRITE command.
* According to command it will do the appropriate action. It will check
* transfer length and if it is not zero then dispatch transfer command again.
* If transfer length is zero then it will indicate the COMPLETION so that
* davinci_spi_bufs function can go ahead.
*/
static irqreturn_t davinci_spi_irq(s32 irq, void *data)
{
struct davinci_spi *dspi = data;
int status;
status = davinci_spi_process_events(dspi);
if (unlikely(status != 0))
clear_io_bits(dspi->base + SPIINT, SPIINT_MASKINT);
if ((!dspi->rcount && !dspi->wcount) || status)
complete(&dspi->done);
return IRQ_HANDLED;
}
static int davinci_spi_request_dma(struct davinci_spi *dspi)
{
dma_cap_mask_t mask;
struct device *sdev = dspi->bitbang.master->dev.parent;
int r;
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
dspi->dma_rx = dma_request_channel(mask, edma_filter_fn,
&dspi->dma_rx_chnum);
if (!dspi->dma_rx) {
dev_err(sdev, "request RX DMA channel failed\n");
r = -ENODEV;
goto rx_dma_failed;
}
dspi->dma_tx = dma_request_channel(mask, edma_filter_fn,
&dspi->dma_tx_chnum);
if (!dspi->dma_tx) {
dev_err(sdev, "request TX DMA channel failed\n");
r = -ENODEV;
goto tx_dma_failed;
}
return 0;
tx_dma_failed:
dma_release_channel(dspi->dma_rx);
rx_dma_failed:
return r;
}
#if defined(CONFIG_OF)
static const struct of_device_id davinci_spi_of_match[] = {
{
.compatible = "ti,dm644x-spi",
},
{
.compatible = "ti,da8xx-spi",
.data = (void *)SPI_VERSION_2,
},
{ },
};
MODULE_DEVICE_TABLE(of, davini_spi_of_match);
/**
* spi_davinci_get_pdata - Get platform data from DTS binding
* @pdev: ptr to platform data
* @dspi: ptr to driver data
*
* Parses and populates pdata in dspi from device tree bindings.
*
* NOTE: Not all platform data params are supported currently.
*/
static int spi_davinci_get_pdata(struct platform_device *pdev,
struct davinci_spi *dspi)
{
struct device_node *node = pdev->dev.of_node;
struct davinci_spi_platform_data *pdata;
unsigned int num_cs, intr_line = 0;
const struct of_device_id *match;
pdata = &dspi->pdata;
pdata->version = SPI_VERSION_1;
match = of_match_device(of_match_ptr(davinci_spi_of_match),
&pdev->dev);
if (!match)
return -ENODEV;
/* match data has the SPI version number for SPI_VERSION_2 */
if (match->data == (void *)SPI_VERSION_2)
pdata->version = SPI_VERSION_2;
/*
* default num_cs is 1 and all chipsel are internal to the chip
* indicated by chip_sel being NULL. GPIO based CS is not
* supported yet in DT bindings.
*/
num_cs = 1;
of_property_read_u32(node, "num-cs", &num_cs);
pdata->num_chipselect = num_cs;
of_property_read_u32(node, "ti,davinci-spi-intr-line", &intr_line);
pdata->intr_line = intr_line;
return 0;
}
#else
#define davinci_spi_of_match NULL
static struct davinci_spi_platform_data
*spi_davinci_get_pdata(struct platform_device *pdev,
struct davinci_spi *dspi)
{
return -ENODEV;
}
#endif
/**
* davinci_spi_probe - probe function for SPI Master Controller
* @pdev: platform_device structure which contains plateform specific data
*
* According to Linux Device Model this function will be invoked by Linux
* with platform_device struct which contains the device specific info.
* This function will map the SPI controller's memory, register IRQ,
* Reset SPI controller and setting its registers to default value.
* It will invoke spi_bitbang_start to create work queue so that client driver
* can register transfer method to work queue.
*/
static int davinci_spi_probe(struct platform_device *pdev)
{
struct spi_master *master;
struct davinci_spi *dspi;
struct davinci_spi_platform_data *pdata;
struct resource *r, *mem;
resource_size_t dma_rx_chan = SPI_NO_RESOURCE;
resource_size_t dma_tx_chan = SPI_NO_RESOURCE;
int i = 0, ret = 0;
u32 spipc0;
master = spi_alloc_master(&pdev->dev, sizeof(struct davinci_spi));
if (master == NULL) {
ret = -ENOMEM;
goto err;
}
dev_set_drvdata(&pdev->dev, master);
dspi = spi_master_get_devdata(master);
if (dspi == NULL) {
ret = -ENOENT;
goto free_master;
}
if (pdev->dev.platform_data) {
pdata = pdev->dev.platform_data;
dspi->pdata = *pdata;
} else {
/* update dspi pdata with that from the DT */
ret = spi_davinci_get_pdata(pdev, dspi);
if (ret < 0)
goto free_master;
}
/* pdata in dspi is now updated and point pdata to that */
pdata = &dspi->pdata;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (r == NULL) {
ret = -ENOENT;
goto free_master;
}
dspi->pbase = r->start;
mem = request_mem_region(r->start, resource_size(r), pdev->name);
if (mem == NULL) {
ret = -EBUSY;
goto free_master;
}
dspi->base = ioremap(r->start, resource_size(r));
if (dspi->base == NULL) {
ret = -ENOMEM;
goto release_region;
}
dspi->irq = platform_get_irq(pdev, 0);
if (dspi->irq <= 0) {
ret = -EINVAL;
goto unmap_io;
}
ret = request_threaded_irq(dspi->irq, davinci_spi_irq, dummy_thread_fn,
0, dev_name(&pdev->dev), dspi);
if (ret)
goto unmap_io;
dspi->bitbang.master = spi_master_get(master);
if (dspi->bitbang.master == NULL) {
ret = -ENODEV;
goto irq_free;
}
dspi->clk = clk_get(&pdev->dev, NULL);
if (IS_ERR(dspi->clk)) {
ret = -ENODEV;
goto put_master;
}
clk_prepare_enable(dspi->clk);
master->dev.of_node = pdev->dev.of_node;
master->bus_num = pdev->id;
master->num_chipselect = pdata->num_chipselect;
master->setup = davinci_spi_setup;
dspi->bitbang.chipselect = davinci_spi_chipselect;
dspi->bitbang.setup_transfer = davinci_spi_setup_transfer;
dspi->version = pdata->version;
dspi->bitbang.flags = SPI_NO_CS | SPI_LSB_FIRST | SPI_LOOP;
if (dspi->version == SPI_VERSION_2)
dspi->bitbang.flags |= SPI_READY;
r = platform_get_resource(pdev, IORESOURCE_DMA, 0);
if (r)
dma_rx_chan = r->start;
r = platform_get_resource(pdev, IORESOURCE_DMA, 1);
if (r)
dma_tx_chan = r->start;
dspi->bitbang.txrx_bufs = davinci_spi_bufs;
if (dma_rx_chan != SPI_NO_RESOURCE &&
dma_tx_chan != SPI_NO_RESOURCE) {
dspi->dma_rx_chnum = dma_rx_chan;
dspi->dma_tx_chnum = dma_tx_chan;
ret = davinci_spi_request_dma(dspi);
if (ret)
goto free_clk;
dev_info(&pdev->dev, "DMA: supported\n");
dev_info(&pdev->dev, "DMA: RX channel: %d, TX channel: %d, "
"event queue: %d\n", dma_rx_chan, dma_tx_chan,
pdata->dma_event_q);
}
dspi->get_rx = davinci_spi_rx_buf_u8;
dspi->get_tx = davinci_spi_tx_buf_u8;
init_completion(&dspi->done);
/* Reset In/OUT SPI module */
iowrite32(0, dspi->base + SPIGCR0);
udelay(100);
iowrite32(1, dspi->base + SPIGCR0);
/* Set up SPIPC0. CS and ENA init is done in davinci_spi_setup */
spipc0 = SPIPC0_DIFUN_MASK | SPIPC0_DOFUN_MASK | SPIPC0_CLKFUN_MASK;
iowrite32(spipc0, dspi->base + SPIPC0);
/* initialize chip selects */
if (pdata->chip_sel) {
for (i = 0; i < pdata->num_chipselect; i++) {
if (pdata->chip_sel[i] != SPI_INTERN_CS)
gpio_direction_output(pdata->chip_sel[i], 1);
}
}
if (pdata->intr_line)
iowrite32(SPI_INTLVL_1, dspi->base + SPILVL);
else
iowrite32(SPI_INTLVL_0, dspi->base + SPILVL);
iowrite32(CS_DEFAULT, dspi->base + SPIDEF);
/* master mode default */
set_io_bits(dspi->base + SPIGCR1, SPIGCR1_CLKMOD_MASK);
set_io_bits(dspi->base + SPIGCR1, SPIGCR1_MASTER_MASK);
set_io_bits(dspi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK);
ret = spi_bitbang_start(&dspi->bitbang);
if (ret)
goto free_dma;
dev_info(&pdev->dev, "Controller at 0x%p\n", dspi->base);
return ret;
free_dma:
dma_release_channel(dspi->dma_rx);
dma_release_channel(dspi->dma_tx);
free_clk:
clk_disable_unprepare(dspi->clk);
clk_put(dspi->clk);
put_master:
spi_master_put(master);
irq_free:
free_irq(dspi->irq, dspi);
unmap_io:
iounmap(dspi->base);
release_region:
release_mem_region(dspi->pbase, resource_size(r));
free_master:
kfree(master);
err:
return ret;
}
/**
* davinci_spi_remove - remove function for SPI Master Controller
* @pdev: platform_device structure which contains plateform specific data
*
* This function will do the reverse action of davinci_spi_probe function
* It will free the IRQ and SPI controller's memory region.
* It will also call spi_bitbang_stop to destroy the work queue which was
* created by spi_bitbang_start.
*/
static int davinci_spi_remove(struct platform_device *pdev)
{
struct davinci_spi *dspi;
struct spi_master *master;
struct resource *r;
master = dev_get_drvdata(&pdev->dev);
dspi = spi_master_get_devdata(master);
spi_bitbang_stop(&dspi->bitbang);
clk_disable_unprepare(dspi->clk);
clk_put(dspi->clk);
spi_master_put(master);
free_irq(dspi->irq, dspi);
iounmap(dspi->base);
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
release_mem_region(dspi->pbase, resource_size(r));
return 0;
}
static struct platform_driver davinci_spi_driver = {
.driver = {
.name = "spi_davinci",
.owner = THIS_MODULE,
.of_match_table = davinci_spi_of_match,
},
.probe = davinci_spi_probe,
.remove = davinci_spi_remove,
};
module_platform_driver(davinci_spi_driver);
MODULE_DESCRIPTION("TI DaVinci SPI Master Controller Driver");
MODULE_LICENSE("GPL");
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