linux/drivers/spi/spi-xilinx.c
Alvaro Gamez Machado e58f7d15e6
spi: xilinx: Add DT support for selecting transfer word width
This core supports either 8, 16 or 32 bits as word width. This value is only
settable on instantiation, and thus we need to support any of them by means
of the device tree.

Signed-off-by: Alvaro Gamez Machado <alvaro.gamez@hazent.com>
Link: https://lore.kernel.org/r/20191024110757.25820-3-alvaro.gamez@hazent.com
Signed-off-by: Mark Brown <broonie@kernel.org>
2019-10-24 12:45:21 +01:00

545 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Xilinx SPI controller driver (master mode only)
*
* Author: MontaVista Software, Inc.
* source@mvista.com
*
* Copyright (c) 2010 Secret Lab Technologies, Ltd.
* Copyright (c) 2009 Intel Corporation
* 2002-2007 (c) MontaVista Software, Inc.
*/
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/spi/xilinx_spi.h>
#include <linux/io.h>
#define XILINX_SPI_MAX_CS 32
#define XILINX_SPI_NAME "xilinx_spi"
/* Register definitions as per "OPB Serial Peripheral Interface (SPI) (v1.00e)
* Product Specification", DS464
*/
#define XSPI_CR_OFFSET 0x60 /* Control Register */
#define XSPI_CR_LOOP 0x01
#define XSPI_CR_ENABLE 0x02
#define XSPI_CR_MASTER_MODE 0x04
#define XSPI_CR_CPOL 0x08
#define XSPI_CR_CPHA 0x10
#define XSPI_CR_MODE_MASK (XSPI_CR_CPHA | XSPI_CR_CPOL | \
XSPI_CR_LSB_FIRST | XSPI_CR_LOOP)
#define XSPI_CR_TXFIFO_RESET 0x20
#define XSPI_CR_RXFIFO_RESET 0x40
#define XSPI_CR_MANUAL_SSELECT 0x80
#define XSPI_CR_TRANS_INHIBIT 0x100
#define XSPI_CR_LSB_FIRST 0x200
#define XSPI_SR_OFFSET 0x64 /* Status Register */
#define XSPI_SR_RX_EMPTY_MASK 0x01 /* Receive FIFO is empty */
#define XSPI_SR_RX_FULL_MASK 0x02 /* Receive FIFO is full */
#define XSPI_SR_TX_EMPTY_MASK 0x04 /* Transmit FIFO is empty */
#define XSPI_SR_TX_FULL_MASK 0x08 /* Transmit FIFO is full */
#define XSPI_SR_MODE_FAULT_MASK 0x10 /* Mode fault error */
#define XSPI_TXD_OFFSET 0x68 /* Data Transmit Register */
#define XSPI_RXD_OFFSET 0x6c /* Data Receive Register */
#define XSPI_SSR_OFFSET 0x70 /* 32-bit Slave Select Register */
/* Register definitions as per "OPB IPIF (v3.01c) Product Specification", DS414
* IPIF registers are 32 bit
*/
#define XIPIF_V123B_DGIER_OFFSET 0x1c /* IPIF global int enable reg */
#define XIPIF_V123B_GINTR_ENABLE 0x80000000
#define XIPIF_V123B_IISR_OFFSET 0x20 /* IPIF interrupt status reg */
#define XIPIF_V123B_IIER_OFFSET 0x28 /* IPIF interrupt enable reg */
#define XSPI_INTR_MODE_FAULT 0x01 /* Mode fault error */
#define XSPI_INTR_SLAVE_MODE_FAULT 0x02 /* Selected as slave while
* disabled */
#define XSPI_INTR_TX_EMPTY 0x04 /* TxFIFO is empty */
#define XSPI_INTR_TX_UNDERRUN 0x08 /* TxFIFO was underrun */
#define XSPI_INTR_RX_FULL 0x10 /* RxFIFO is full */
#define XSPI_INTR_RX_OVERRUN 0x20 /* RxFIFO was overrun */
#define XSPI_INTR_TX_HALF_EMPTY 0x40 /* TxFIFO is half empty */
#define XIPIF_V123B_RESETR_OFFSET 0x40 /* IPIF reset register */
#define XIPIF_V123B_RESET_MASK 0x0a /* the value to write */
struct xilinx_spi {
/* bitbang has to be first */
struct spi_bitbang bitbang;
struct completion done;
void __iomem *regs; /* virt. address of the control registers */
int irq;
u8 *rx_ptr; /* pointer in the Tx buffer */
const u8 *tx_ptr; /* pointer in the Rx buffer */
u8 bytes_per_word;
int buffer_size; /* buffer size in words */
u32 cs_inactive; /* Level of the CS pins when inactive*/
unsigned int (*read_fn)(void __iomem *);
void (*write_fn)(u32, void __iomem *);
};
static void xspi_write32(u32 val, void __iomem *addr)
{
iowrite32(val, addr);
}
static unsigned int xspi_read32(void __iomem *addr)
{
return ioread32(addr);
}
static void xspi_write32_be(u32 val, void __iomem *addr)
{
iowrite32be(val, addr);
}
static unsigned int xspi_read32_be(void __iomem *addr)
{
return ioread32be(addr);
}
static void xilinx_spi_tx(struct xilinx_spi *xspi)
{
u32 data = 0;
if (!xspi->tx_ptr) {
xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
return;
}
switch (xspi->bytes_per_word) {
case 1:
data = *(u8 *)(xspi->tx_ptr);
break;
case 2:
data = *(u16 *)(xspi->tx_ptr);
break;
case 4:
data = *(u32 *)(xspi->tx_ptr);
break;
}
xspi->write_fn(data, xspi->regs + XSPI_TXD_OFFSET);
xspi->tx_ptr += xspi->bytes_per_word;
}
static void xilinx_spi_rx(struct xilinx_spi *xspi)
{
u32 data = xspi->read_fn(xspi->regs + XSPI_RXD_OFFSET);
if (!xspi->rx_ptr)
return;
switch (xspi->bytes_per_word) {
case 1:
*(u8 *)(xspi->rx_ptr) = data;
break;
case 2:
*(u16 *)(xspi->rx_ptr) = data;
break;
case 4:
*(u32 *)(xspi->rx_ptr) = data;
break;
}
xspi->rx_ptr += xspi->bytes_per_word;
}
static void xspi_init_hw(struct xilinx_spi *xspi)
{
void __iomem *regs_base = xspi->regs;
/* Reset the SPI device */
xspi->write_fn(XIPIF_V123B_RESET_MASK,
regs_base + XIPIF_V123B_RESETR_OFFSET);
/* Enable the transmit empty interrupt, which we use to determine
* progress on the transmission.
*/
xspi->write_fn(XSPI_INTR_TX_EMPTY,
regs_base + XIPIF_V123B_IIER_OFFSET);
/* Disable the global IPIF interrupt */
xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);
/* Deselect the slave on the SPI bus */
xspi->write_fn(0xffff, regs_base + XSPI_SSR_OFFSET);
/* Disable the transmitter, enable Manual Slave Select Assertion,
* put SPI controller into master mode, and enable it */
xspi->write_fn(XSPI_CR_MANUAL_SSELECT | XSPI_CR_MASTER_MODE |
XSPI_CR_ENABLE | XSPI_CR_TXFIFO_RESET | XSPI_CR_RXFIFO_RESET,
regs_base + XSPI_CR_OFFSET);
}
static void xilinx_spi_chipselect(struct spi_device *spi, int is_on)
{
struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
u16 cr;
u32 cs;
if (is_on == BITBANG_CS_INACTIVE) {
/* Deselect the slave on the SPI bus */
xspi->write_fn(xspi->cs_inactive, xspi->regs + XSPI_SSR_OFFSET);
return;
}
/* Set the SPI clock phase and polarity */
cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET) & ~XSPI_CR_MODE_MASK;
if (spi->mode & SPI_CPHA)
cr |= XSPI_CR_CPHA;
if (spi->mode & SPI_CPOL)
cr |= XSPI_CR_CPOL;
if (spi->mode & SPI_LSB_FIRST)
cr |= XSPI_CR_LSB_FIRST;
if (spi->mode & SPI_LOOP)
cr |= XSPI_CR_LOOP;
xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
/* We do not check spi->max_speed_hz here as the SPI clock
* frequency is not software programmable (the IP block design
* parameter)
*/
cs = xspi->cs_inactive;
cs ^= BIT(spi->chip_select);
/* Activate the chip select */
xspi->write_fn(cs, xspi->regs + XSPI_SSR_OFFSET);
}
/* spi_bitbang requires custom setup_transfer() to be defined if there is a
* custom txrx_bufs().
*/
static int xilinx_spi_setup_transfer(struct spi_device *spi,
struct spi_transfer *t)
{
struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
if (spi->mode & SPI_CS_HIGH)
xspi->cs_inactive &= ~BIT(spi->chip_select);
else
xspi->cs_inactive |= BIT(spi->chip_select);
return 0;
}
static int xilinx_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
{
struct xilinx_spi *xspi = spi_master_get_devdata(spi->master);
int remaining_words; /* the number of words left to transfer */
bool use_irq = false;
u16 cr = 0;
/* We get here with transmitter inhibited */
xspi->tx_ptr = t->tx_buf;
xspi->rx_ptr = t->rx_buf;
remaining_words = t->len / xspi->bytes_per_word;
if (xspi->irq >= 0 && remaining_words > xspi->buffer_size) {
u32 isr;
use_irq = true;
/* Inhibit irq to avoid spurious irqs on tx_empty*/
cr = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
xspi->regs + XSPI_CR_OFFSET);
/* ACK old irqs (if any) */
isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET);
if (isr)
xspi->write_fn(isr,
xspi->regs + XIPIF_V123B_IISR_OFFSET);
/* Enable the global IPIF interrupt */
xspi->write_fn(XIPIF_V123B_GINTR_ENABLE,
xspi->regs + XIPIF_V123B_DGIER_OFFSET);
reinit_completion(&xspi->done);
}
while (remaining_words) {
int n_words, tx_words, rx_words;
u32 sr;
int stalled;
n_words = min(remaining_words, xspi->buffer_size);
tx_words = n_words;
while (tx_words--)
xilinx_spi_tx(xspi);
/* Start the transfer by not inhibiting the transmitter any
* longer
*/
if (use_irq) {
xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
wait_for_completion(&xspi->done);
/* A transmit has just completed. Process received data
* and check for more data to transmit. Always inhibit
* the transmitter while the Isr refills the transmit
* register/FIFO, or make sure it is stopped if we're
* done.
*/
xspi->write_fn(cr | XSPI_CR_TRANS_INHIBIT,
xspi->regs + XSPI_CR_OFFSET);
sr = XSPI_SR_TX_EMPTY_MASK;
} else
sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
/* Read out all the data from the Rx FIFO */
rx_words = n_words;
stalled = 10;
while (rx_words) {
if (rx_words == n_words && !(stalled--) &&
!(sr & XSPI_SR_TX_EMPTY_MASK) &&
(sr & XSPI_SR_RX_EMPTY_MASK)) {
dev_err(&spi->dev,
"Detected stall. Check C_SPI_MODE and C_SPI_MEMORY\n");
xspi_init_hw(xspi);
return -EIO;
}
if ((sr & XSPI_SR_TX_EMPTY_MASK) && (rx_words > 1)) {
xilinx_spi_rx(xspi);
rx_words--;
continue;
}
sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
if (!(sr & XSPI_SR_RX_EMPTY_MASK)) {
xilinx_spi_rx(xspi);
rx_words--;
}
}
remaining_words -= n_words;
}
if (use_irq) {
xspi->write_fn(0, xspi->regs + XIPIF_V123B_DGIER_OFFSET);
xspi->write_fn(cr, xspi->regs + XSPI_CR_OFFSET);
}
return t->len;
}
/* This driver supports single master mode only. Hence Tx FIFO Empty
* is the only interrupt we care about.
* Receive FIFO Overrun, Transmit FIFO Underrun, Mode Fault, and Slave Mode
* Fault are not to happen.
*/
static irqreturn_t xilinx_spi_irq(int irq, void *dev_id)
{
struct xilinx_spi *xspi = dev_id;
u32 ipif_isr;
/* Get the IPIF interrupts, and clear them immediately */
ipif_isr = xspi->read_fn(xspi->regs + XIPIF_V123B_IISR_OFFSET);
xspi->write_fn(ipif_isr, xspi->regs + XIPIF_V123B_IISR_OFFSET);
if (ipif_isr & XSPI_INTR_TX_EMPTY) { /* Transmission completed */
complete(&xspi->done);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static int xilinx_spi_find_buffer_size(struct xilinx_spi *xspi)
{
u8 sr;
int n_words = 0;
/*
* Before the buffer_size detection we reset the core
* to make sure we start with a clean state.
*/
xspi->write_fn(XIPIF_V123B_RESET_MASK,
xspi->regs + XIPIF_V123B_RESETR_OFFSET);
/* Fill the Tx FIFO with as many words as possible */
do {
xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
sr = xspi->read_fn(xspi->regs + XSPI_SR_OFFSET);
n_words++;
} while (!(sr & XSPI_SR_TX_FULL_MASK));
return n_words;
}
static const struct of_device_id xilinx_spi_of_match[] = {
{ .compatible = "xlnx,axi-quad-spi-1.00.a", },
{ .compatible = "xlnx,xps-spi-2.00.a", },
{ .compatible = "xlnx,xps-spi-2.00.b", },
{}
};
MODULE_DEVICE_TABLE(of, xilinx_spi_of_match);
static int xilinx_spi_probe(struct platform_device *pdev)
{
struct xilinx_spi *xspi;
struct xspi_platform_data *pdata;
struct resource *res;
int ret, num_cs = 0, bits_per_word;
struct spi_master *master;
u32 tmp;
u8 i;
pdata = dev_get_platdata(&pdev->dev);
if (pdata) {
num_cs = pdata->num_chipselect;
bits_per_word = pdata->bits_per_word;
} else {
of_property_read_u32(pdev->dev.of_node, "xlnx,num-ss-bits",
&num_cs);
ret = of_property_read_u32(pdev->dev.of_node,
"xlnx,num-transfer-bits",
&bits_per_word);
if (ret)
bits_per_word = 8;
}
if (!num_cs) {
dev_err(&pdev->dev,
"Missing slave select configuration data\n");
return -EINVAL;
}
if (num_cs > XILINX_SPI_MAX_CS) {
dev_err(&pdev->dev, "Invalid number of spi slaves\n");
return -EINVAL;
}
master = spi_alloc_master(&pdev->dev, sizeof(struct xilinx_spi));
if (!master)
return -ENODEV;
/* the spi->mode bits understood by this driver: */
master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP |
SPI_CS_HIGH;
xspi = spi_master_get_devdata(master);
xspi->cs_inactive = 0xffffffff;
xspi->bitbang.master = master;
xspi->bitbang.chipselect = xilinx_spi_chipselect;
xspi->bitbang.setup_transfer = xilinx_spi_setup_transfer;
xspi->bitbang.txrx_bufs = xilinx_spi_txrx_bufs;
init_completion(&xspi->done);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
xspi->regs = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(xspi->regs)) {
ret = PTR_ERR(xspi->regs);
goto put_master;
}
master->bus_num = pdev->id;
master->num_chipselect = num_cs;
master->dev.of_node = pdev->dev.of_node;
/*
* Detect endianess on the IP via loop bit in CR. Detection
* must be done before reset is sent because incorrect reset
* value generates error interrupt.
* Setup little endian helper functions first and try to use them
* and check if bit was correctly setup or not.
*/
xspi->read_fn = xspi_read32;
xspi->write_fn = xspi_write32;
xspi->write_fn(XSPI_CR_LOOP, xspi->regs + XSPI_CR_OFFSET);
tmp = xspi->read_fn(xspi->regs + XSPI_CR_OFFSET);
tmp &= XSPI_CR_LOOP;
if (tmp != XSPI_CR_LOOP) {
xspi->read_fn = xspi_read32_be;
xspi->write_fn = xspi_write32_be;
}
master->bits_per_word_mask = SPI_BPW_MASK(bits_per_word);
xspi->bytes_per_word = bits_per_word / 8;
xspi->buffer_size = xilinx_spi_find_buffer_size(xspi);
xspi->irq = platform_get_irq(pdev, 0);
if (xspi->irq < 0 && xspi->irq != -ENXIO) {
ret = xspi->irq;
goto put_master;
} else if (xspi->irq >= 0) {
/* Register for SPI Interrupt */
ret = devm_request_irq(&pdev->dev, xspi->irq, xilinx_spi_irq, 0,
dev_name(&pdev->dev), xspi);
if (ret)
goto put_master;
}
/* SPI controller initializations */
xspi_init_hw(xspi);
ret = spi_bitbang_start(&xspi->bitbang);
if (ret) {
dev_err(&pdev->dev, "spi_bitbang_start FAILED\n");
goto put_master;
}
dev_info(&pdev->dev, "at 0x%08llX mapped to 0x%p, irq=%d\n",
(unsigned long long)res->start, xspi->regs, xspi->irq);
if (pdata) {
for (i = 0; i < pdata->num_devices; i++)
spi_new_device(master, pdata->devices + i);
}
platform_set_drvdata(pdev, master);
return 0;
put_master:
spi_master_put(master);
return ret;
}
static int xilinx_spi_remove(struct platform_device *pdev)
{
struct spi_master *master = platform_get_drvdata(pdev);
struct xilinx_spi *xspi = spi_master_get_devdata(master);
void __iomem *regs_base = xspi->regs;
spi_bitbang_stop(&xspi->bitbang);
/* Disable all the interrupts just in case */
xspi->write_fn(0, regs_base + XIPIF_V123B_IIER_OFFSET);
/* Disable the global IPIF interrupt */
xspi->write_fn(0, regs_base + XIPIF_V123B_DGIER_OFFSET);
spi_master_put(xspi->bitbang.master);
return 0;
}
/* work with hotplug and coldplug */
MODULE_ALIAS("platform:" XILINX_SPI_NAME);
static struct platform_driver xilinx_spi_driver = {
.probe = xilinx_spi_probe,
.remove = xilinx_spi_remove,
.driver = {
.name = XILINX_SPI_NAME,
.of_match_table = xilinx_spi_of_match,
},
};
module_platform_driver(xilinx_spi_driver);
MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
MODULE_DESCRIPTION("Xilinx SPI driver");
MODULE_LICENSE("GPL");