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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Renesas RZ/V2M Clocked Serial Interface (CSI) driver
*
* Copyright (C) 2023 Renesas Electronics Corporation
*/
#include <linux/bits.h>
#include <linux/clk.h>
#include <linux/count_zeros.h>
#include <linux/interrupt.h>
#include <linux/iopoll.h>
#include <linux/log2.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/reset.h>
#include <linux/spi/spi.h>
#include <linux/units.h>
/* Registers */
#define CSI_MODE 0x00 /* CSI mode control */
#define CSI_CLKSEL 0x04 /* CSI clock select */
#define CSI_CNT 0x08 /* CSI control */
#define CSI_INT 0x0C /* CSI interrupt status */
#define CSI_IFIFOL 0x10 /* CSI receive FIFO level display */
#define CSI_OFIFOL 0x14 /* CSI transmit FIFO level display */
#define CSI_IFIFO 0x18 /* CSI receive window */
#define CSI_OFIFO 0x1C /* CSI transmit window */
#define CSI_FIFOTRG 0x20 /* CSI FIFO trigger level */
/* CSI_MODE */
#define CSI_MODE_CSIE BIT(7)
#define CSI_MODE_TRMD BIT(6)
#define CSI_MODE_CCL BIT(5)
#define CSI_MODE_DIR BIT(4)
#define CSI_MODE_CSOT BIT(0)
#define CSI_MODE_SETUP 0x00000040
/* CSI_CLKSEL */
#define CSI_CLKSEL_SS_ENA BIT(19)
#define CSI_CLKSEL_SS_POL BIT(18)
#define CSI_CLKSEL_SS (CSI_CLKSEL_SS_ENA | CSI_CLKSEL_SS_POL)
#define CSI_CLKSEL_CKP BIT(17)
#define CSI_CLKSEL_DAP BIT(16)
#define CSI_CLKSEL_MODE (CSI_CLKSEL_CKP|CSI_CLKSEL_DAP)
#define CSI_CLKSEL_SLAVE BIT(15)
#define CSI_CLKSEL_CKS GENMASK(14, 1)
/* CSI_CNT */
#define CSI_CNT_CSIRST BIT(28)
#define CSI_CNT_R_TRGEN BIT(19)
#define CSI_CNT_UNDER_E BIT(13)
#define CSI_CNT_OVERF_E BIT(12)
#define CSI_CNT_TREND_E BIT(9)
#define CSI_CNT_CSIEND_E BIT(8)
#define CSI_CNT_T_TRGR_E BIT(4)
#define CSI_CNT_R_TRGR_E BIT(0)
/* CSI_INT */
#define CSI_INT_UNDER BIT(13)
#define CSI_INT_OVERF BIT(12)
#define CSI_INT_TREND BIT(9)
#define CSI_INT_CSIEND BIT(8)
#define CSI_INT_T_TRGR BIT(4)
#define CSI_INT_R_TRGR BIT(0)
/* CSI_FIFOTRG */
#define CSI_FIFOTRG_R_TRG GENMASK(2, 0)
#define CSI_FIFO_SIZE_BYTES 32U
#define CSI_FIFO_HALF_SIZE 16U
#define CSI_EN_DIS_TIMEOUT_US 100
/*
* Clock "csiclk" gets divided by 2 * CSI_CLKSEL_CKS in order to generate the
* serial clock (output from master), with CSI_CLKSEL_CKS ranging from 0x1 (that
* means "csiclk" is divided by 2) to 0x3FFF ("csiclk" is divided by 32766).
*/
#define CSI_CKS_MAX GENMASK(13, 0)
#define UNDERRUN_ERROR BIT(0)
#define OVERFLOW_ERROR BIT(1)
#define TX_TIMEOUT_ERROR BIT(2)
#define RX_TIMEOUT_ERROR BIT(3)
#define CSI_MAX_SPI_SCKO (8 * HZ_PER_MHZ)
#define CSI_CLKSEL_SS_DISABLED 0
#define CSI_CLKSEL_SS_ENABLED_ACTIVE_LOW BIT(1)
#define CSI_CLKSEL_SS_ENABLED_ACTIVE_HIGH GENMASK(1, 0)
struct rzv2m_csi_priv {
void __iomem *base;
struct clk *csiclk;
struct clk *pclk;
struct device *dev;
struct spi_controller *controller;
const void *txbuf;
void *rxbuf;
unsigned int buffer_len;
unsigned int bytes_sent;
unsigned int bytes_received;
unsigned int bytes_to_transfer;
unsigned int words_to_transfer;
unsigned int bytes_per_word;
wait_queue_head_t wait;
u32 errors;
u32 status;
bool target_aborted;
bool use_ss_pin;
};
static void rzv2m_csi_reg_write_bit(const struct rzv2m_csi_priv *csi,
int reg_offs, int bit_mask, u32 value)
{
int nr_zeros;
u32 tmp;
nr_zeros = count_trailing_zeros(bit_mask);
value <<= nr_zeros;
tmp = (readl(csi->base + reg_offs) & ~bit_mask) | value;
writel(tmp, csi->base + reg_offs);
}
static int rzv2m_csi_sw_reset(struct rzv2m_csi_priv *csi, int assert)
{
u32 reg;
rzv2m_csi_reg_write_bit(csi, CSI_CNT, CSI_CNT_CSIRST, assert);
if (!assert)
return 0;
return readl_poll_timeout(csi->base + CSI_MODE, reg,
!(reg & CSI_MODE_CSOT), 0,
CSI_EN_DIS_TIMEOUT_US);
}
static int rzv2m_csi_start_stop_operation(const struct rzv2m_csi_priv *csi,
int enable, bool wait)
{
u32 reg;
rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_CSIE, enable);
if (enable || !wait)
return 0;
return readl_poll_timeout(csi->base + CSI_MODE, reg,
!(reg & CSI_MODE_CSOT), 0,
CSI_EN_DIS_TIMEOUT_US);
}
static int rzv2m_csi_fill_txfifo(struct rzv2m_csi_priv *csi)
{
unsigned int i;
if (readl(csi->base + CSI_OFIFOL))
return -EIO;
if (csi->bytes_per_word == 2) {
const u16 *buf = csi->txbuf;
for (i = 0; i < csi->words_to_transfer; i++)
writel(buf[i], csi->base + CSI_OFIFO);
} else {
const u8 *buf = csi->txbuf;
for (i = 0; i < csi->words_to_transfer; i++)
writel(buf[i], csi->base + CSI_OFIFO);
}
csi->txbuf += csi->bytes_to_transfer;
csi->bytes_sent += csi->bytes_to_transfer;
return 0;
}
static int rzv2m_csi_read_rxfifo(struct rzv2m_csi_priv *csi)
{
unsigned int i;
if (readl(csi->base + CSI_IFIFOL) != csi->bytes_to_transfer)
return -EIO;
if (csi->bytes_per_word == 2) {
u16 *buf = csi->rxbuf;
for (i = 0; i < csi->words_to_transfer; i++)
buf[i] = (u16)readl(csi->base + CSI_IFIFO);
} else {
u8 *buf = csi->rxbuf;
for (i = 0; i < csi->words_to_transfer; i++)
buf[i] = (u8)readl(csi->base + CSI_IFIFO);
}
csi->rxbuf += csi->bytes_to_transfer;
csi->bytes_received += csi->bytes_to_transfer;
return 0;
}
static inline void rzv2m_csi_empty_rxfifo(struct rzv2m_csi_priv *csi)
{
unsigned int i;
for (i = 0; i < csi->words_to_transfer; i++)
readl(csi->base + CSI_IFIFO);
}
static inline void rzv2m_csi_calc_current_transfer(struct rzv2m_csi_priv *csi)
{
unsigned int bytes_transferred = max(csi->bytes_received, csi->bytes_sent);
unsigned int bytes_remaining = csi->buffer_len - bytes_transferred;
unsigned int to_transfer;
if (csi->txbuf)
/*
* Leaving a little bit of headroom in the FIFOs makes it very
* hard to raise an overflow error (which is only possible
* when IP transmits and receives at the same time).
*/
to_transfer = min(CSI_FIFO_HALF_SIZE, bytes_remaining);
else
to_transfer = min(CSI_FIFO_SIZE_BYTES, bytes_remaining);
if (csi->bytes_per_word == 2)
to_transfer >>= 1;
/*
* We can only choose a trigger level from a predefined set of values.
* This will pick a value that is the greatest possible integer that's
* less than or equal to the number of bytes we need to transfer.
* This may result in multiple smaller transfers.
*/
csi->words_to_transfer = rounddown_pow_of_two(to_transfer);
if (csi->bytes_per_word == 2)
csi->bytes_to_transfer = csi->words_to_transfer << 1;
else
csi->bytes_to_transfer = csi->words_to_transfer;
}
static inline void rzv2m_csi_set_rx_fifo_trigger_level(struct rzv2m_csi_priv *csi)
{
rzv2m_csi_reg_write_bit(csi, CSI_FIFOTRG, CSI_FIFOTRG_R_TRG,
ilog2(csi->words_to_transfer));
}
static inline void rzv2m_csi_enable_rx_trigger(struct rzv2m_csi_priv *csi,
bool enable)
{
rzv2m_csi_reg_write_bit(csi, CSI_CNT, CSI_CNT_R_TRGEN, enable);
}
static void rzv2m_csi_disable_irqs(const struct rzv2m_csi_priv *csi,
u32 enable_bits)
{
u32 cnt = readl(csi->base + CSI_CNT);
writel(cnt & ~enable_bits, csi->base + CSI_CNT);
}
static void rzv2m_csi_disable_all_irqs(struct rzv2m_csi_priv *csi)
{
rzv2m_csi_disable_irqs(csi, CSI_CNT_R_TRGR_E | CSI_CNT_T_TRGR_E |
CSI_CNT_CSIEND_E | CSI_CNT_TREND_E |
CSI_CNT_OVERF_E | CSI_CNT_UNDER_E);
}
static inline void rzv2m_csi_clear_irqs(struct rzv2m_csi_priv *csi, u32 irqs)
{
writel(irqs, csi->base + CSI_INT);
}
static void rzv2m_csi_clear_all_irqs(struct rzv2m_csi_priv *csi)
{
rzv2m_csi_clear_irqs(csi, CSI_INT_UNDER | CSI_INT_OVERF |
CSI_INT_TREND | CSI_INT_CSIEND | CSI_INT_T_TRGR |
CSI_INT_R_TRGR);
}
static void rzv2m_csi_enable_irqs(struct rzv2m_csi_priv *csi, u32 enable_bits)
{
u32 cnt = readl(csi->base + CSI_CNT);
writel(cnt | enable_bits, csi->base + CSI_CNT);
}
static int rzv2m_csi_wait_for_interrupt(struct rzv2m_csi_priv *csi,
u32 wait_mask, u32 enable_bits)
{
int ret;
rzv2m_csi_enable_irqs(csi, enable_bits);
if (spi_controller_is_target(csi->controller)) {
ret = wait_event_interruptible(csi->wait,
((csi->status & wait_mask) == wait_mask) ||
csi->errors || csi->target_aborted);
if (ret || csi->target_aborted)
ret = -EINTR;
} else {
ret = wait_event_timeout(csi->wait,
((csi->status & wait_mask) == wait_mask) ||
csi->errors, HZ) == 0 ? -ETIMEDOUT : 0;
}
rzv2m_csi_disable_irqs(csi, enable_bits);
if (csi->errors)
return -EIO;
return ret;
}
static inline int rzv2m_csi_wait_for_rx_ready(struct rzv2m_csi_priv *csi)
{
int ret;
if (readl(csi->base + CSI_IFIFOL) >= csi->bytes_to_transfer)
return 0;
ret = rzv2m_csi_wait_for_interrupt(csi, CSI_INT_R_TRGR,
CSI_CNT_R_TRGR_E);
if (ret == -ETIMEDOUT)
csi->errors |= RX_TIMEOUT_ERROR;
return ret;
}
static irqreturn_t rzv2m_csi_irq_handler(int irq, void *data)
{
struct rzv2m_csi_priv *csi = data;
csi->status = readl(csi->base + CSI_INT);
rzv2m_csi_disable_irqs(csi, csi->status);
if (csi->status & CSI_INT_OVERF)
csi->errors |= OVERFLOW_ERROR;
if (csi->status & CSI_INT_UNDER)
csi->errors |= UNDERRUN_ERROR;
wake_up(&csi->wait);
return IRQ_HANDLED;
}
static void rzv2m_csi_setup_clock(struct rzv2m_csi_priv *csi, u32 spi_hz)
{
unsigned long csiclk_rate = clk_get_rate(csi->csiclk);
unsigned long pclk_rate = clk_get_rate(csi->pclk);
unsigned long csiclk_rate_limit = pclk_rate >> 1;
u32 cks;
/*
* There is a restriction on the frequency of CSICLK, it has to be <=
* PCLK / 2.
*/
if (csiclk_rate > csiclk_rate_limit) {
clk_set_rate(csi->csiclk, csiclk_rate >> 1);
csiclk_rate = clk_get_rate(csi->csiclk);
} else if ((csiclk_rate << 1) <= csiclk_rate_limit) {
clk_set_rate(csi->csiclk, csiclk_rate << 1);
csiclk_rate = clk_get_rate(csi->csiclk);
}
spi_hz = spi_hz > CSI_MAX_SPI_SCKO ? CSI_MAX_SPI_SCKO : spi_hz;
cks = DIV_ROUND_UP(csiclk_rate, spi_hz << 1);
if (cks > CSI_CKS_MAX)
cks = CSI_CKS_MAX;
dev_dbg(csi->dev, "SPI clk rate is %ldHz\n", csiclk_rate / (cks << 1));
rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_CKS, cks);
}
static void rzv2m_csi_setup_operating_mode(struct rzv2m_csi_priv *csi,
struct spi_transfer *t)
{
if (t->rx_buf && !t->tx_buf)
/* Reception-only mode */
rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_TRMD, 0);
else
/* Send and receive mode */
rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_TRMD, 1);
csi->bytes_per_word = t->bits_per_word / 8;
rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_CCL,
csi->bytes_per_word == 2);
}
static int rzv2m_csi_setup(struct spi_device *spi)
{
struct rzv2m_csi_priv *csi = spi_controller_get_devdata(spi->controller);
u32 slave_selection = CSI_CLKSEL_SS_DISABLED;
int ret;
rzv2m_csi_sw_reset(csi, 0);
writel(CSI_MODE_SETUP, csi->base + CSI_MODE);
/* Setup clock polarity and phase timing */
rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_MODE,
~spi->mode & SPI_MODE_X_MASK);
/* Setup serial data order */
rzv2m_csi_reg_write_bit(csi, CSI_MODE, CSI_MODE_DIR,
!!(spi->mode & SPI_LSB_FIRST));
/* Set the role, 1 for target and 0 for host */
rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_SLAVE,
!!spi_controller_is_target(csi->controller));
if (csi->use_ss_pin)
slave_selection = spi->mode & SPI_CS_HIGH ?
CSI_CLKSEL_SS_ENABLED_ACTIVE_HIGH :
CSI_CLKSEL_SS_ENABLED_ACTIVE_LOW;
/* Configure the slave selection (SS) pin */
rzv2m_csi_reg_write_bit(csi, CSI_CLKSEL, CSI_CLKSEL_SS, slave_selection);
/* Give the IP a SW reset */
ret = rzv2m_csi_sw_reset(csi, 1);
if (ret)
return ret;
rzv2m_csi_sw_reset(csi, 0);
/*
* We need to enable the communication so that the clock will settle
* for the right polarity before enabling the CS.
*/
rzv2m_csi_start_stop_operation(csi, 1, false);
udelay(10);
rzv2m_csi_start_stop_operation(csi, 0, false);
return 0;
}
static int rzv2m_csi_pio_transfer(struct rzv2m_csi_priv *csi)
{
bool tx_completed = !csi->txbuf;
bool rx_completed = !csi->rxbuf;
int ret = 0;
/* Make sure the TX FIFO is empty */
writel(0, csi->base + CSI_OFIFOL);
/* Make sure the RX FIFO is empty */
writel(0, csi->base + CSI_IFIFOL);
csi->bytes_sent = 0;
csi->bytes_received = 0;
csi->errors = 0;
csi->target_aborted = false;
rzv2m_csi_disable_all_irqs(csi);
rzv2m_csi_clear_all_irqs(csi);
rzv2m_csi_enable_rx_trigger(csi, true);
while (!tx_completed || !rx_completed) {
/*
* Decide how many words we are going to transfer during
* this cycle (for both TX and RX), then set the RX FIFO trigger
* level accordingly. No need to set a trigger level for the
* TX FIFO, as this IP comes with an interrupt that fires when
* the TX FIFO is empty.
*/
rzv2m_csi_calc_current_transfer(csi);
rzv2m_csi_set_rx_fifo_trigger_level(csi);
rzv2m_csi_enable_irqs(csi, CSI_INT_OVERF | CSI_INT_UNDER);
writel(readl(csi->base + CSI_INT), csi->base + CSI_INT);
csi->status = 0;
/* TX */
if (csi->txbuf) {
ret = rzv2m_csi_fill_txfifo(csi);
if (ret)
break;
if (csi->bytes_sent == csi->buffer_len)
tx_completed = true;
}
rzv2m_csi_start_stop_operation(csi, 1, false);
/*
* Make sure the RX FIFO contains the desired number of words.
* We then either flush its content, or we copy it onto
* csi->rxbuf.
*/
ret = rzv2m_csi_wait_for_rx_ready(csi);
if (ret)
break;
if (!spi_controller_is_target(csi->controller))
rzv2m_csi_start_stop_operation(csi, 0, false);
/* RX */
if (csi->rxbuf) {
ret = rzv2m_csi_read_rxfifo(csi);
if (ret)
break;
if (csi->bytes_received == csi->buffer_len)
rx_completed = true;
} else {
rzv2m_csi_empty_rxfifo(csi);
}
if (csi->errors) {
ret = -EIO;
break;
}
}
rzv2m_csi_start_stop_operation(csi, 0, true);
rzv2m_csi_disable_all_irqs(csi);
rzv2m_csi_enable_rx_trigger(csi, false);
rzv2m_csi_clear_all_irqs(csi);
return ret;
}
static int rzv2m_csi_transfer_one(struct spi_controller *controller,
struct spi_device *spi,
struct spi_transfer *transfer)
{
struct rzv2m_csi_priv *csi = spi_controller_get_devdata(controller);
struct device *dev = csi->dev;
int ret;
csi->txbuf = transfer->tx_buf;
csi->rxbuf = transfer->rx_buf;
csi->buffer_len = transfer->len;
rzv2m_csi_setup_operating_mode(csi, transfer);
if (!spi_controller_is_target(csi->controller))
rzv2m_csi_setup_clock(csi, transfer->speed_hz);
ret = rzv2m_csi_pio_transfer(csi);
if (ret) {
if (csi->errors & UNDERRUN_ERROR)
dev_err(dev, "Underrun error\n");
if (csi->errors & OVERFLOW_ERROR)
dev_err(dev, "Overflow error\n");
if (csi->errors & TX_TIMEOUT_ERROR)
dev_err(dev, "TX timeout error\n");
if (csi->errors & RX_TIMEOUT_ERROR)
dev_err(dev, "RX timeout error\n");
}
return ret;
}
static int rzv2m_csi_target_abort(struct spi_controller *ctlr)
{
struct rzv2m_csi_priv *csi = spi_controller_get_devdata(ctlr);
csi->target_aborted = true;
wake_up(&csi->wait);
return 0;
}
static int rzv2m_csi_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct spi_controller *controller;
struct device *dev = &pdev->dev;
struct rzv2m_csi_priv *csi;
struct reset_control *rstc;
bool target_mode;
int irq;
int ret;
target_mode = of_property_read_bool(np, "spi-slave");
if (target_mode)
controller = devm_spi_alloc_target(dev, sizeof(*csi));
else
controller = devm_spi_alloc_host(dev, sizeof(*csi));
if (!controller)
return -ENOMEM;
csi = spi_controller_get_devdata(controller);
platform_set_drvdata(pdev, csi);
csi->use_ss_pin = false;
if (spi_controller_is_target(controller) &&
!of_property_read_bool(np, "renesas,csi-no-ss"))
csi->use_ss_pin = true;
csi->dev = dev;
csi->controller = controller;
csi->target_aborted = false;
csi->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(csi->base))
return PTR_ERR(csi->base);
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
csi->csiclk = devm_clk_get(dev, "csiclk");
if (IS_ERR(csi->csiclk))
return dev_err_probe(dev, PTR_ERR(csi->csiclk),
"could not get csiclk\n");
csi->pclk = devm_clk_get(dev, "pclk");
if (IS_ERR(csi->pclk))
return dev_err_probe(dev, PTR_ERR(csi->pclk),
"could not get pclk\n");
rstc = devm_reset_control_get_shared(dev, NULL);
if (IS_ERR(rstc))
return dev_err_probe(dev, PTR_ERR(rstc), "Missing reset ctrl\n");
init_waitqueue_head(&csi->wait);
controller->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_CS_HIGH;
controller->bits_per_word_mask = SPI_BPW_MASK(16) | SPI_BPW_MASK(8);
controller->setup = rzv2m_csi_setup;
controller->transfer_one = rzv2m_csi_transfer_one;
controller->use_gpio_descriptors = true;
controller->target_abort = rzv2m_csi_target_abort;
device_set_node(&controller->dev, dev_fwnode(dev));
ret = devm_request_irq(dev, irq, rzv2m_csi_irq_handler, 0,
dev_name(dev), csi);
if (ret)
return dev_err_probe(dev, ret, "cannot request IRQ\n");
/*
* The reset also affects other HW that is not under the control
* of Linux. Therefore, all we can do is make sure the reset is
* deasserted.
*/
reset_control_deassert(rstc);
/* Make sure the IP is in SW reset state */
ret = rzv2m_csi_sw_reset(csi, 1);
if (ret)
return ret;
ret = clk_prepare_enable(csi->csiclk);
if (ret)
return dev_err_probe(dev, ret, "could not enable csiclk\n");
ret = spi_register_controller(controller);
if (ret) {
clk_disable_unprepare(csi->csiclk);
return dev_err_probe(dev, ret, "register controller failed\n");
}
return 0;
}
static void rzv2m_csi_remove(struct platform_device *pdev)
{
struct rzv2m_csi_priv *csi = platform_get_drvdata(pdev);
spi_unregister_controller(csi->controller);
rzv2m_csi_sw_reset(csi, 1);
clk_disable_unprepare(csi->csiclk);
}
static const struct of_device_id rzv2m_csi_match[] = {
{ .compatible = "renesas,rzv2m-csi" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, rzv2m_csi_match);
static struct platform_driver rzv2m_csi_drv = {
.probe = rzv2m_csi_probe,
.remove_new = rzv2m_csi_remove,
.driver = {
.name = "rzv2m_csi",
.of_match_table = rzv2m_csi_match,
},
};
module_platform_driver(rzv2m_csi_drv);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Fabrizio Castro <castro.fabrizio.jz@renesas.com>");
MODULE_DESCRIPTION("Clocked Serial Interface Driver");