// SPDX-License-Identifier: (GPL-2.0)
/*
* Microchip CoreSPI SPI controller driver
*
* Copyright (c) 2018-2022 Microchip Technology Inc. and its subsidiaries
*
* Author: Daire McNamara <[email protected]>
* Author: Conor Dooley <[email protected]>
*
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#define MAX_LEN (0xffff)
#define MAX_CS (1)
#define DEFAULT_FRAMESIZE (8)
#define FIFO_DEPTH (32)
#define CLK_GEN_MODE1_MAX (255)
#define CLK_GEN_MODE0_MAX (15)
#define CLK_GEN_MIN (0)
#define MODE_X_MASK_SHIFT (24)
#define CONTROL_ENABLE BIT(0)
#define CONTROL_MASTER BIT(1)
#define CONTROL_RX_DATA_INT BIT(4)
#define CONTROL_TX_DATA_INT BIT(5)
#define CONTROL_RX_OVER_INT BIT(6)
#define CONTROL_TX_UNDER_INT BIT(7)
#define CONTROL_SPO BIT(24)
#define CONTROL_SPH BIT(25)
#define CONTROL_SPS BIT(26)
#define CONTROL_FRAMEURUN BIT(27)
#define CONTROL_CLKMODE BIT(28)
#define CONTROL_BIGFIFO BIT(29)
#define CONTROL_OENOFF BIT(30)
#define CONTROL_RESET BIT(31)
#define CONTROL_MODE_MASK GENMASK(3, 2)
#define MOTOROLA_MODE (0)
#define CONTROL_FRAMECNT_MASK GENMASK(23, 8)
#define CONTROL_FRAMECNT_SHIFT (8)
#define STATUS_ACTIVE BIT(14)
#define STATUS_SSEL BIT(13)
#define STATUS_FRAMESTART BIT(12)
#define STATUS_TXFIFO_EMPTY_NEXT_READ BIT(11)
#define STATUS_TXFIFO_EMPTY BIT(10)
#define STATUS_TXFIFO_FULL_NEXT_WRITE BIT(9)
#define STATUS_TXFIFO_FULL BIT(8)
#define STATUS_RXFIFO_EMPTY_NEXT_READ BIT(7)
#define STATUS_RXFIFO_EMPTY BIT(6)
#define STATUS_RXFIFO_FULL_NEXT_WRITE BIT(5)
#define STATUS_RXFIFO_FULL BIT(4)
#define STATUS_TX_UNDERRUN BIT(3)
#define STATUS_RX_OVERFLOW BIT(2)
#define STATUS_RXDAT_RXED BIT(1)
#define STATUS_TXDAT_SENT BIT(0)
#define INT_TXDONE BIT(0)
#define INT_RXRDY BIT(1)
#define INT_RX_CHANNEL_OVERFLOW BIT(2)
#define INT_TX_CHANNEL_UNDERRUN BIT(3)
#define INT_ENABLE_MASK (CONTROL_RX_DATA_INT | CONTROL_TX_DATA_INT | \
CONTROL_RX_OVER_INT | CONTROL_TX_UNDER_INT)
#define REG_CONTROL (0x00)
#define REG_FRAME_SIZE (0x04)
#define FRAME_SIZE_MASK GENMASK(5, 0)
#define REG_STATUS (0x08)
#define REG_INT_CLEAR (0x0c)
#define REG_RX_DATA (0x10)
#define REG_TX_DATA (0x14)
#define REG_CLK_GEN (0x18)
#define REG_SLAVE_SELECT (0x1c)
#define SSEL_MASK GENMASK(7, 0)
#define SSEL_DIRECT BIT(8)
#define SSELOUT_SHIFT 9
#define SSELOUT BIT(SSELOUT_SHIFT)
#define REG_MIS (0x20)
#define REG_RIS (0x24)
#define REG_CONTROL2 (0x28)
#define REG_COMMAND (0x2c)
#define COMMAND_CLRFRAMECNT BIT(4)
#define COMMAND_TXFIFORST BIT(3)
#define COMMAND_RXFIFORST BIT(2)
#define REG_PKTSIZE (0x30)
#define REG_CMD_SIZE (0x34)
#define REG_HWSTATUS (0x38)
#define REG_STAT8 (0x3c)
#define REG_CTRL2 (0x48)
#define REG_FRAMESUP (0x50)
struct mchp_corespi {
void __iomem *regs;
struct clk *clk;
const u8 *tx_buf;
u8 *rx_buf;
u32 clk_gen; /* divider for spi output clock generated by the controller */
u32 clk_mode;
u32 pending_slave_select;
int irq;
int tx_len;
int rx_len;
int n_bytes;
};
static inline u32 mchp_corespi_read(struct mchp_corespi *spi, unsigned int reg)
{
return readl(spi->regs + reg);
}
static inline void mchp_corespi_write(struct mchp_corespi *spi, unsigned int reg, u32 val)
{
writel(val, spi->regs + reg);
}
static inline void mchp_corespi_disable(struct mchp_corespi *spi)
{
u32 control = mchp_corespi_read(spi, REG_CONTROL);
control &= ~CONTROL_ENABLE;
mchp_corespi_write(spi, REG_CONTROL, control);
}
static inline void mchp_corespi_read_fifo(struct mchp_corespi *spi)
{
while (spi->rx_len >= spi->n_bytes && !(mchp_corespi_read(spi, REG_STATUS) & STATUS_RXFIFO_EMPTY)) {
u32 data = mchp_corespi_read(spi, REG_RX_DATA);
spi->rx_len -= spi->n_bytes;
if (!spi->rx_buf)
continue;
if (spi->n_bytes == 4)
*((u32 *)spi->rx_buf) = data;
else if (spi->n_bytes == 2)
*((u16 *)spi->rx_buf) = data;
else
*spi->rx_buf = data;
spi->rx_buf += spi->n_bytes;
}
}
static void mchp_corespi_enable_ints(struct mchp_corespi *spi)
{
u32 control = mchp_corespi_read(spi, REG_CONTROL);
control |= INT_ENABLE_MASK;
mchp_corespi_write(spi, REG_CONTROL, control);
}
static void mchp_corespi_disable_ints(struct mchp_corespi *spi)
{
u32 control = mchp_corespi_read(spi, REG_CONTROL);
control &= ~INT_ENABLE_MASK;
mchp_corespi_write(spi, REG_CONTROL, control);
}
static inline void mchp_corespi_set_xfer_size(struct mchp_corespi *spi, int len)
{
u32 control;
u32 lenpart;
u32 frames = mchp_corespi_read(spi, REG_FRAMESUP);
/*
* Writing to FRAMECNT in REG_CONTROL will reset the frame count, taking
* a shortcut requires an explicit clear.
*/
if (frames == len) {
mchp_corespi_write(spi, REG_COMMAND, COMMAND_CLRFRAMECNT);
return;
}
/*
* The lower 16 bits of the frame count are stored in the control reg
* for legacy reasons, but the upper 16 written to a different register:
* FRAMESUP. While both the upper and lower bits can be *READ* from the
* FRAMESUP register, writing to the lower 16 bits is (supposedly) a NOP.
*
* The driver used to disable the controller while modifying the frame
* count, and mask off the lower 16 bits of len while writing to
* FRAMES_UP. When the driver was changed to disable the controller as
* infrequently as possible, it was discovered that the logic of
* lenpart = len & 0xffff_0000
* write(REG_FRAMESUP, lenpart)
* would actually write zeros into the lower 16 bits on an mpfs250t-es,
* despite documentation stating these bits were read-only.
* Writing len unmasked into FRAMES_UP ensures those bits aren't zeroed
* on an mpfs250t-es and will be a NOP for the lower 16 bits on hardware
* that matches the documentation.
*/
lenpart = len & 0xffff;
control = mchp_corespi_read(spi, REG_CONTROL);
control &= ~CONTROL_FRAMECNT_MASK;
control |= lenpart << CONTROL_FRAMECNT_SHIFT;
mchp_corespi_write(spi, REG_CONTROL, control);
mchp_corespi_write(spi, REG_FRAMESUP, len);
}
static inline void mchp_corespi_write_fifo(struct mchp_corespi *spi)
{
int fifo_max, i = 0;
fifo_max = DIV_ROUND_UP(min(spi->tx_len, FIFO_DEPTH), spi->n_bytes);
mchp_corespi_set_xfer_size(spi, fifo_max);
while ((i < fifo_max) && !(mchp_corespi_read(spi, REG_STATUS) & STATUS_TXFIFO_FULL)) {
u32 word;
if (spi->n_bytes == 4)
word = spi->tx_buf ? *((u32 *)spi->tx_buf) : 0xaa;
else if (spi->n_bytes == 2)
word = spi->tx_buf ? *((u16 *)spi->tx_buf) : 0xaa;
else
word = spi->tx_buf ? *spi->tx_buf : 0xaa;
mchp_corespi_write(spi, REG_TX_DATA, word);
if (spi->tx_buf)
spi->tx_buf += spi->n_bytes;
i++;
}
spi->tx_len -= i * spi->n_bytes;
}
static inline void mchp_corespi_set_framesize(struct mchp_corespi *spi, int bt)
{
u32 frame_size = mchp_corespi_read(spi, REG_FRAME_SIZE);
u32 control;
if ((frame_size & FRAME_SIZE_MASK) == bt)
return;
/*
* Disable the SPI controller. Writes to the frame size have
* no effect when the controller is enabled.
*/
control = mchp_corespi_read(spi, REG_CONTROL);
control &= ~CONTROL_ENABLE;
mchp_corespi_write(spi, REG_CONTROL, control);
mchp_corespi_write(spi, REG_FRAME_SIZE, bt);
control |= CONTROL_ENABLE;
mchp_corespi_write(spi, REG_CONTROL, control);
}
static void mchp_corespi_set_cs(struct spi_device *spi, bool disable)
{
u32 reg;
struct mchp_corespi *corespi = spi_controller_get_devdata(spi->controller);
reg = mchp_corespi_read(corespi, REG_SLAVE_SELECT);
reg &= ~BIT(spi_get_chipselect(spi, 0));
reg |= !disable << spi_get_chipselect(spi, 0);
corespi->pending_slave_select = reg;
/*
* Only deassert chip select immediately. Writing to some registers
* requires the controller to be disabled, which results in the
* output pins being tristated and can cause the SCLK and MOSI lines
* to transition. Therefore asserting the chip select is deferred
* until just before writing to the TX FIFO, to ensure the device
* doesn't see any spurious clock transitions whilst CS is enabled.
*/
if (((spi->mode & SPI_CS_HIGH) == 0) == disable)
mchp_corespi_write(corespi, REG_SLAVE_SELECT, reg);
}
static int mchp_corespi_setup(struct spi_device *spi)
{
struct mchp_corespi *corespi = spi_controller_get_devdata(spi->controller);
u32 reg;
if (spi_is_csgpiod(spi))
return 0;
/*
* Active high targets need to be specifically set to their inactive
* states during probe by adding them to the "control group" & thus
* driving their select line low.
*/
if (spi->mode & SPI_CS_HIGH) {
reg = mchp_corespi_read(corespi, REG_SLAVE_SELECT);
reg |= BIT(spi_get_chipselect(spi, 0));
corespi->pending_slave_select = reg;
mchp_corespi_write(corespi, REG_SLAVE_SELECT, reg);
}
return 0;
}
static void mchp_corespi_init(struct spi_controller *host, struct mchp_corespi *spi)
{
unsigned long clk_hz;
u32 control = mchp_corespi_read(spi, REG_CONTROL);
control &= ~CONTROL_ENABLE;
mchp_corespi_write(spi, REG_CONTROL, control);
control |= CONTROL_MASTER;
control &= ~CONTROL_MODE_MASK;
control |= MOTOROLA_MODE;
/*
* The controller must be configured so that it doesn't remove Chip
* Select until the entire message has been transferred, even if at
* some points TX FIFO becomes empty.
*
* BIGFIFO mode is also enabled, which sets the fifo depth to 32 frames
* for the 8 bit transfers that this driver uses.
*/
control |= CONTROL_SPS | CONTROL_BIGFIFO;
mchp_corespi_write(spi, REG_CONTROL, control);
mchp_corespi_set_framesize(spi, DEFAULT_FRAMESIZE);
/* max. possible spi clock rate is the apb clock rate */
clk_hz = clk_get_rate(spi->clk);
host->max_speed_hz = clk_hz;
mchp_corespi_enable_ints(spi);
/*
* It is required to enable direct mode, otherwise control over the chip
* select is relinquished to the hardware. SSELOUT is enabled too so we
* can deal with active high targets.
*/
spi->pending_slave_select = SSELOUT | SSEL_DIRECT;
mchp_corespi_write(spi, REG_SLAVE_SELECT, spi->pending_slave_select);
control = mchp_corespi_read(spi, REG_CONTROL);
control &= ~CONTROL_RESET;
control |= CONTROL_ENABLE;
mchp_corespi_write(spi, REG_CONTROL, control);
}
static inline void mchp_corespi_set_clk_gen(struct mchp_corespi *spi)
{
u32 control;
control = mchp_corespi_read(spi, REG_CONTROL);
if (spi->clk_mode)
control |= CONTROL_CLKMODE;
else
control &= ~CONTROL_CLKMODE;
mchp_corespi_write(spi, REG_CLK_GEN, spi->clk_gen);
mchp_corespi_write(spi, REG_CONTROL, control);
}
static inline void mchp_corespi_set_mode(struct mchp_corespi *spi, unsigned int mode)
{
u32 mode_val;
u32 control = mchp_corespi_read(spi, REG_CONTROL);
switch (mode & SPI_MODE_X_MASK) {
case SPI_MODE_0:
mode_val = 0;
break;
case SPI_MODE_1:
mode_val = CONTROL_SPH;
break;
case SPI_MODE_2:
mode_val = CONTROL_SPO;
break;
case SPI_MODE_3:
mode_val = CONTROL_SPH | CONTROL_SPO;
break;
}
/*
* Disable the SPI controller. Writes to the frame protocol have
* no effect when the controller is enabled.
*/
control &= ~CONTROL_ENABLE;
mchp_corespi_write(spi, REG_CONTROL, control);
control &= ~(SPI_MODE_X_MASK << MODE_X_MASK_SHIFT);
control |= mode_val;
mchp_corespi_write(spi, REG_CONTROL, control);
control |= CONTROL_ENABLE;
mchp_corespi_write(spi, REG_CONTROL, control);
}
static irqreturn_t mchp_corespi_interrupt(int irq, void *dev_id)
{
struct spi_controller *host = dev_id;
struct mchp_corespi *spi = spi_controller_get_devdata(host);
u32 intfield = mchp_corespi_read(spi, REG_MIS) & 0xf;
bool finalise = false;
/* Interrupt line may be shared and not for us at all */
if (intfield == 0)
return IRQ_NONE;
if (intfield & INT_TXDONE)
mchp_corespi_write(spi, REG_INT_CLEAR, INT_TXDONE);
if (intfield & INT_RXRDY) {
mchp_corespi_write(spi, REG_INT_CLEAR, INT_RXRDY);
if (spi->rx_len)
mchp_corespi_read_fifo(spi);
}
if (!spi->rx_len && !spi->tx_len)
finalise = true;
if (intfield & INT_RX_CHANNEL_OVERFLOW) {
mchp_corespi_write(spi, REG_INT_CLEAR, INT_RX_CHANNEL_OVERFLOW);
finalise = true;
dev_err(&host->dev,
"%s: RX OVERFLOW: rxlen: %d, txlen: %d\n", __func__,
spi->rx_len, spi->tx_len);
}
if (intfield & INT_TX_CHANNEL_UNDERRUN) {
mchp_corespi_write(spi, REG_INT_CLEAR, INT_TX_CHANNEL_UNDERRUN);
finalise = true;
dev_err(&host->dev,
"%s: TX UNDERFLOW: rxlen: %d, txlen: %d\n", __func__,
spi->rx_len, spi->tx_len);
}
if (finalise)
spi_finalize_current_transfer(host);
return IRQ_HANDLED;
}
static int mchp_corespi_calculate_clkgen(struct mchp_corespi *spi,
unsigned long target_hz)
{
unsigned long clk_hz, spi_hz, clk_gen;
clk_hz = clk_get_rate(spi->clk);
if (!clk_hz)
return -EINVAL;
spi_hz = min(target_hz, clk_hz);
/*
* There are two possible clock modes for the controller generated
* clock's division ratio:
* CLK_MODE = 0: 1 / (2^(CLK_GEN + 1)) where CLK_GEN = 0 to 15.
* CLK_MODE = 1: 1 / (2 * CLK_GEN + 1) where CLK_GEN = 0 to 255.
* First try mode 1, fall back to 0 and if we have tried both modes and
* we /still/ can't get a good setting, we then throw the toys out of
* the pram and give up
* clk_gen is the register name for the clock divider on MPFS.
*/
clk_gen = DIV_ROUND_UP(clk_hz, 2 * spi_hz) - 1;
if (clk_gen > CLK_GEN_MODE1_MAX || clk_gen <= CLK_GEN_MIN) {
clk_gen = DIV_ROUND_UP(clk_hz, spi_hz);
clk_gen = fls(clk_gen) - 1;
if (clk_gen > CLK_GEN_MODE0_MAX)
return -EINVAL;
spi->clk_mode = 0;
} else {
spi->clk_mode = 1;
}
spi->clk_gen = clk_gen;
return 0;
}
static int mchp_corespi_transfer_one(struct spi_controller *host,
struct spi_device *spi_dev,
struct spi_transfer *xfer)
{
struct mchp_corespi *spi = spi_controller_get_devdata(host);
int ret;
ret = mchp_corespi_calculate_clkgen(spi, (unsigned long)xfer->speed_hz);
if (ret) {
dev_err(&host->dev, "failed to set clk_gen for target %u Hz\n", xfer->speed_hz);
return ret;
}
mchp_corespi_set_clk_gen(spi);
spi->tx_buf = xfer->tx_buf;
spi->rx_buf = xfer->rx_buf;
spi->tx_len = xfer->len;
spi->rx_len = xfer->len;
spi->n_bytes = roundup_pow_of_two(DIV_ROUND_UP(xfer->bits_per_word, BITS_PER_BYTE));
mchp_corespi_set_framesize(spi, xfer->bits_per_word);
mchp_corespi_write(spi, REG_COMMAND, COMMAND_RXFIFORST | COMMAND_TXFIFORST);
mchp_corespi_write(spi, REG_SLAVE_SELECT, spi->pending_slave_select);
while (spi->tx_len)
mchp_corespi_write_fifo(spi);
return 1;
}
static int mchp_corespi_prepare_message(struct spi_controller *host,
struct spi_message *msg)
{
struct spi_device *spi_dev = msg->spi;
struct mchp_corespi *spi = spi_controller_get_devdata(host);
mchp_corespi_set_mode(spi, spi_dev->mode);
return 0;
}
static int mchp_corespi_probe(struct platform_device *pdev)
{
struct spi_controller *host;
struct mchp_corespi *spi;
struct resource *res;
u32 num_cs;
int ret = 0;
host = devm_spi_alloc_host(&pdev->dev, sizeof(*spi));
if (!host)
return dev_err_probe(&pdev->dev, -ENOMEM,
"unable to allocate host for SPI controller\n");
platform_set_drvdata(pdev, host);
if (of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs))
num_cs = MAX_CS;
host->num_chipselect = num_cs;
host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
host->use_gpio_descriptors = true;
host->setup = mchp_corespi_setup;
host->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
host->transfer_one = mchp_corespi_transfer_one;
host->prepare_message = mchp_corespi_prepare_message;
host->set_cs = mchp_corespi_set_cs;
host->dev.of_node = pdev->dev.of_node;
spi = spi_controller_get_devdata(host);
spi->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
if (IS_ERR(spi->regs))
return PTR_ERR(spi->regs);
spi->irq = platform_get_irq(pdev, 0);
if (spi->irq < 0)
return spi->irq;
ret = devm_request_irq(&pdev->dev, spi->irq, mchp_corespi_interrupt,
IRQF_SHARED, dev_name(&pdev->dev), host);
if (ret)
return dev_err_probe(&pdev->dev, ret,
"could not request irq\n");
spi->clk = devm_clk_get_enabled(&pdev->dev, NULL);
if (IS_ERR(spi->clk))
return dev_err_probe(&pdev->dev, PTR_ERR(spi->clk),
"could not get clk\n");
mchp_corespi_init(host, spi);
ret = devm_spi_register_controller(&pdev->dev, host);
if (ret) {
mchp_corespi_disable(spi);
return dev_err_probe(&pdev->dev, ret,
"unable to register host for SPI controller\n");
}
dev_info(&pdev->dev, "Registered SPI controller %d\n", host->bus_num);
return 0;
}
static void mchp_corespi_remove(struct platform_device *pdev)
{
struct spi_controller *host = platform_get_drvdata(pdev);
struct mchp_corespi *spi = spi_controller_get_devdata(host);
mchp_corespi_disable_ints(spi);
mchp_corespi_disable(spi);
}
#define MICROCHIP_SPI_PM_OPS (NULL)
/*
* Platform driver data structure
*/
#if defined(CONFIG_OF)
static const struct of_device_id mchp_corespi_dt_ids[] = {
{ .compatible = "microchip,mpfs-spi" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mchp_corespi_dt_ids);
#endif
static struct platform_driver mchp_corespi_driver = {
.probe = mchp_corespi_probe,
.driver = {
.name = "microchip-corespi",
.pm = MICROCHIP_SPI_PM_OPS,
.of_match_table = of_match_ptr(mchp_corespi_dt_ids),
},
.remove_new = mchp_corespi_remove,
};
module_platform_driver(mchp_corespi_driver);
MODULE_DESCRIPTION("Microchip coreSPI SPI controller driver");
MODULE_AUTHOR("Daire McNamara <[email protected]>");
MODULE_AUTHOR("Conor Dooley <[email protected]>");
MODULE_LICENSE("GPL");
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