[PATCH v2 2/3] spi: axiado: Add driver for Axiado SPI DB controller

Vladimir Moravcevic
2025-09-29T08:59:05Z

The Axiado SPI controller is present in AX3000 SoC and Evaluation Board.
This controller is operating in Host only mode.

Signed-off-by: Vladimir Moravcevic <vmoravcevic@axiado.com>
Signed-off-by: Prasad Bolisetty <pbolisetty@axiado.com>
---
drivers/spi/Kconfig | 10 +
drivers/spi/Makefile | 1 +
drivers/spi/spi-axiado.c | 1029 ++++++++++++++++++++++++++++++++++++++++++++++
drivers/spi/spi-axiado.h | 129 ++++++
4 files changed, 1169 insertions(+)

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 891729c9c5642a08212a0080db619512c5b57bbd..1e6443f5272a4b239542ea93a94b53693c1c51f4 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -194,6 +194,16 @@ config SPI_AXI_SPI_ENGINE
It is part of the SPI Engine framework that is used in some Analog Devices
reference designs for FPGAs.

+config SPI_AXIADO
+ tristate "Axiado DB-H SPI controller"
+ depends on SPI_MEM
+ help
+ This enables support for the SPI controller found on AX3000 SoC.
+
+ The implementation supports host-only mode and does not provide target
+ functionality. It is intended for use cases where the SoC acts as the SPI
+ host, communicating with peripheral devices such as flash memory.
+
config SPI_BCM2835
tristate "BCM2835 SPI controller"
depends on GPIOLIB
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 062c85989c8c9652822ec377228398249dd2304b..7f1e7bf3dce41789e3d2ef31c0f78609d403f8ca 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -31,6 +31,7 @@ obj-$(CONFIG_SPI_AT91_USART) += spi-at91-usart.o
obj-$(CONFIG_SPI_ATH79) += spi-ath79.o
obj-$(CONFIG_SPI_AU1550) += spi-au1550.o
obj-$(CONFIG_SPI_AXI_SPI_ENGINE) += spi-axi-spi-engine.o
+obj-$(CONFIG_SPI_AXIADO) += spi-axiado.o
obj-$(CONFIG_SPI_BCM2835) += spi-bcm2835.o
obj-$(CONFIG_SPI_BCM2835AUX) += spi-bcm2835aux.o
obj-$(CONFIG_SPI_BCM63XX) += spi-bcm63xx.o
diff --git a/drivers/spi/spi-axiado.c b/drivers/spi/spi-axiado.c
new file mode 100644
index 0000000000000000000000000000000000000000..b3335610ffea6b0d956521220d8ae917bd4fde9d
--- /dev/null
+++ b/drivers/spi/spi-axiado.c
@@ -0,0 +1,1029 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Axiado SPI controller driver (Host mode only)
+ *
+ * Copyright (C) 2022-2025 Axiado Corporation (or its affiliates). All rights reserved.
+ *
+ */
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi-mem.h>
+#include <linux/sizes.h>
+
+#include "spi-axiado.h"
+
+/**
+ * ax_spi_read - Register Read - 32 bit per word
+ * @xspi: Pointer to the ax_spi structure
+ * @offset: Register offset address
+ *
+ * @return: Returns the value of that register
+ */
+static inline u32 ax_spi_read(struct ax_spi *xspi, u32 offset)
+{
+ return readl_relaxed(xspi->regs + offset);
+}
+
+/**
+ * ax_spi_write - Register write - 32 bit per word
+ * @xspi: Pointer to the ax_spi structure
+ * @offset: Register offset address
+ * @val: Value to write into that register
+ */
+static inline void ax_spi_write(struct ax_spi *xspi, u32 offset, u32 val)
+{
+ writel_relaxed(val, xspi->regs + offset);
+}
+
+/**
+ * ax_spi_write_b - Register Read - 8 bit per word
+ * @xspi: Pointer to the ax_spi structure
+ * @offset: Register offset address
+ * @val: Value to write into that register
+ */
+static inline void ax_spi_write_b(struct ax_spi *xspi, u32 offset, u8 val)
+{
+ writeb_relaxed(val, xspi->regs + offset);
+}
+
+/**
+ * ax_spi_init_hw - Initialize the hardware and configure the SPI controller
+ * @xspi: Pointer to the ax_spi structure
+ *
+ * * On reset the SPI controller is configured to be in host mode.
+ * In host mode baud rate divisor is set to 4, threshold value for TX FIFO
+ * not full interrupt is set to 1 and size of the word to be transferred as 8 bit.
+ *
+ * This function initializes the SPI controller to disable and clear all the
+ * interrupts, enable manual target select and manual start, deselect all the
+ * chip select lines, and enable the SPI controller.
+ */
+static void ax_spi_init_hw(struct ax_spi *xspi)
+{
+ u32 reg_value;
+
+ /* Clear CR1 */
+ ax_spi_write(xspi, AX_SPI_CR1, AX_SPI_CR1_CLR);
+
+ /* CR1 - CPO CHP MSS SCE SCR */
+ reg_value = ax_spi_read(xspi, AX_SPI_CR1);
+ reg_value |= AX_SPI_CR1_SCR | AX_SPI_CR1_SCE;
+
+ ax_spi_write(xspi, AX_SPI_CR1, reg_value);
+
+ /* CR2 - MTE SRD SWD SSO */
+ reg_value = ax_spi_read(xspi, AX_SPI_CR2);
+ reg_value |= AX_SPI_CR2_SWD | AX_SPI_CR2_SRD;
+
+ ax_spi_write(xspi, AX_SPI_CR2, reg_value);
+
+ /* CR3 - Reserverd bits S3W SDL */
+ ax_spi_write(xspi, AX_SPI_CR3, AX_SPI_CR3_SDL);
+
+ /* SCDR - Reserved bits SCS SCD */
+ ax_spi_write(xspi, AX_SPI_SCDR, (AX_SPI_SCDR_SCS | AX_SPI_SCD_DEFAULT));
+
+ /* IMR */
+ ax_spi_write(xspi, AX_SPI_IMR, AX_SPI_IMR_CLR);
+
+ /* ISR - Clear all the interrupt */
+ ax_spi_write(xspi, AX_SPI_ISR, AX_SPI_ISR_CLR);
+}
+
+/**
+ * ax_spi_chipselect - Select or deselect the chip select line
+ * @spi: Pointer to the spi_device structure
+ * @is_high: Select(0) or deselect (1) the chip select line
+ */
+static void ax_spi_chipselect(struct spi_device *spi, bool is_high)
+{
+ struct ax_spi *xspi = spi_controller_get_devdata(spi->controller);
+ u32 ctrl_reg;
+
+ ctrl_reg = ax_spi_read(xspi, AX_SPI_CR2);
+ /* Reset the chip select */
+ ctrl_reg &= ~AX_SPI_DEFAULT_TS_MASK;
+ ctrl_reg |= spi_get_chipselect(spi, 0);
+
+ ax_spi_write(xspi, AX_SPI_CR2, ctrl_reg);
+}
+
+/**
+ * ax_spi_config_clock_mode - Sets clock polarity and phase
+ * @spi: Pointer to the spi_device structure
+ *
+ * Sets the requested clock polarity and phase.
+ */
+static void ax_spi_config_clock_mode(struct spi_device *spi)
+{
+ struct ax_spi *xspi = spi_controller_get_devdata(spi->controller);
+ u32 ctrl_reg, new_ctrl_reg;
+
+ new_ctrl_reg = ax_spi_read(xspi, AX_SPI_CR1);
+ ctrl_reg = new_ctrl_reg;
+
+ /* Set the SPI clock phase and clock polarity */
+ new_ctrl_reg &= ~(AX_SPI_CR1_CPHA | AX_SPI_CR1_CPOL);
+ if (spi->mode & SPI_CPHA)
+ new_ctrl_reg |= AX_SPI_CR1_CPHA;
+ if (spi->mode & SPI_CPOL)
+ new_ctrl_reg |= AX_SPI_CR1_CPOL;
+
+ if (new_ctrl_reg != ctrl_reg)
+ ax_spi_write(xspi, AX_SPI_CR1, new_ctrl_reg);
+ ax_spi_write(xspi, AX_SPI_CR1, 0x03);
+}
+
+/**
+ * ax_spi_config_clock_freq - Sets clock frequency
+ * @spi: Pointer to the spi_device structure
+ * @transfer: Pointer to the spi_transfer structure which provides
+ * information about next transfer setup parameters
+ *
+ * Sets the requested clock frequency.
+ * Note: If the requested frequency is not an exact match with what can be
+ * obtained using the prescalar value the driver sets the clock frequency which
+ * is lower than the requested frequency (maximum lower) for the transfer. If
+ * the requested frequency is higher or lower than that is supported by the SPI
+ * controller the driver will set the highest or lowest frequency supported by
+ * controller.
+ */
+static void ax_spi_config_clock_freq(struct spi_device *spi,
+ struct spi_transfer *transfer)
+{
+ struct ax_spi *xspi = spi_controller_get_devdata(spi->controller);
+
+ u32 ctrl_reg;
+
+ /* xspi->clk_rate - AMBA Slave clock frequency
+ * transfer->speed_hz - Slave clock required frequency
+ * As per data sheet - SCD = (AMBA Slave clock/SCK) - 2
+ */
+ ctrl_reg = (xspi->clk_rate / transfer->speed_hz) - 2;
+
+ /* As per Digital Blocks datasheet clock frequency range
+ * Min - 244KHz
+ * Max - 62.5MHz
+ * If the user configures less than Min value,
+ * it will configured to 244KHz by default
+ */
+ if (ctrl_reg <= AX_SPI_SCD_MIN)
+ ax_spi_write(xspi, AX_SPI_SCDR, ctrl_reg | AX_SPI_SCDR_SCS);
+ else
+ ax_spi_write(xspi, AX_SPI_SCDR, AX_SPI_SCD_MIN | AX_SPI_SCDR_SCS);
+}
+
+/**
+ * ax_spi_setup_transfer - Configure SPI controller for specified transfer
+ * @spi: Pointer to the spi_device structure
+ * @transfer: Pointer to the spi_transfer structure which provides
+ * information about next transfer setup parameters
+ *
+ * Sets the operational mode of SPI controller for the next SPI transfer and
+ * sets the requested clock frequency.
+ *
+ */
+static void ax_spi_setup_transfer(struct spi_device *spi,
+ struct spi_transfer *transfer)
+{
+ struct ax_spi *xspi = spi_controller_get_devdata(spi->controller);
+
+ ax_spi_config_clock_freq(spi, transfer);
+
+ dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u clock speed\n",
+ __func__, spi->mode, spi->bits_per_word,
+ xspi->speed_hz);
+}
+
+/**
+ * ax_spi_fill_tx_fifo - Fills the TX FIFO with as many bytes as possible
+ * @xspi: Pointer to the ax_spi structure
+ */
+static void ax_spi_fill_tx_fifo(struct ax_spi *xspi)
+{
+ unsigned long trans_cnt = 0;
+
+ while ((trans_cnt < xspi->tx_fifo_depth) &&
+ (xspi->tx_bytes > 0)) {
+ /* When xspi in busy condition, bytes may send failed,
+ * then spi control did't work thoroughly, add one byte delay
+ */
+ if (ax_spi_read(xspi, AX_SPI_IVR) & AX_SPI_IVR_TFOV)
+ usleep_range(10, 10);
+ if (xspi->tx_buf)
+ ax_spi_write_b(xspi, AX_SPI_TXFIFO, *xspi->tx_buf++);
+ else
+ ax_spi_write_b(xspi, AX_SPI_TXFIFO, 0);
+
+ xspi->tx_bytes--;
+ trans_cnt++;
+ }
+}
+/**
+ * ax_spi_get_rx_byte - Gets a byte from the RX FIFO buffer
+ * @xspi: Controller private data (struct ax_spi *)
+ *
+ * This function handles the logic of extracting bytes from the 32-bit RX FIFO.
+ * It reads a new 32-bit word from AX_SPI_RXFIFO only when the current buffered
+ * word has been fully processed (all 4 bytes extracted). It then extracts
+ * bytes one by one, assuming the controller is little-endian.
+ *
+ * Returns: The next 8-bit byte read from the RX FIFO stream.
+ */
+static u8 ax_spi_get_rx_byte_for_irq(struct ax_spi *xspi)
+{
+ u8 byte_val;
+
+ /* If all bytes from the current 32-bit word have been extracted,
+ * read a new word from the hardware RX FIFO.
+ */
+ if (xspi->bytes_left_in_current_rx_word_for_irq == 0) {
+ xspi->current_rx_fifo_word_for_irq = ax_spi_read(xspi, AX_SPI_RXFIFO);
+ xspi->bytes_left_in_current_rx_word_for_irq = 4; // A new 32-bit word has 4 bytes
+ }
+
+ /* Extract the least significant byte from the current 32-bit word */
+ byte_val = (u8)(xspi->current_rx_fifo_word_for_irq & 0xFF);
+
+ /* Shift the word right by 8 bits to prepare the next byte for extraction */
+ xspi->current_rx_fifo_word_for_irq >>= 8;
+ xspi->bytes_left_in_current_rx_word_for_irq--;
+
+ return byte_val;
+}
+
+/*
+ * Helper function to process received bytes and check for transfer completion.
+ * This avoids code duplication and centralizes the completion logic.
+ * Returns true if the transfer was finalized.
+ */
+static bool ax_spi_process_rx_and_finalize(struct spi_controller *ctlr)
+{
+ struct ax_spi *xspi = spi_controller_get_devdata(ctlr);
+
+ /* Process any remaining bytes in the RX FIFO */
+ u32 avail_bytes = ax_spi_read(xspi, AX_SPI_RX_FBCAR);
+
+ // This loop handles bytes that are already staged from a previous word read
+ while (xspi->bytes_left_in_current_rx_word_for_irq &&
+ (xspi->rx_copy_remaining || xspi->rx_discard)) {
+ u8 b = ax_spi_get_rx_byte_for_irq(xspi);
+
+ if (xspi->rx_discard) {
+ xspi->rx_discard--;
+ } else {
+ *xspi->rx_buf++ = b;
+ xspi->rx_copy_remaining--;
+ }
+ }
+
+ // This loop processes new words directly from the FIFO
+ while (avail_bytes >= 4 && (xspi->rx_copy_remaining || xspi->rx_discard)) {
+ // This function should handle reading from the FIFO
+ u8 b = ax_spi_get_rx_byte_for_irq(xspi);
+
+ if (xspi->rx_discard) {
+ xspi->rx_discard--;
+ } else {
+ *xspi->rx_buf++ = b;
+ xspi->rx_copy_remaining--;
+ }
+ // ax_spi_get_rx_byte_for_irq fetches a new word when needed
+ // and updates internal state.
+ if (xspi->bytes_left_in_current_rx_word_for_irq == 3)
+ avail_bytes -= 4;
+ }
+
+ /*
+ * Completion Check: The transfer is truly complete if all expected
+ * RX bytes have been copied or discarded.
+ */
+ if (xspi->rx_copy_remaining == 0 && xspi->rx_discard == 0) {
+ /*
+ * Defensive drain: If for some reason there are leftover bytes
+ * in the HW FIFO after we've logically finished,
+ * read and discard them to prevent them from corrupting the next transfer.
+ * This should be a bounded operation.
+ */
+ int safety_words = AX_SPI_RX_FIFO_DRAIN_LIMIT; // Limit to avoid getting stuck
+
+ while (ax_spi_read(xspi, AX_SPI_RX_FBCAR) > 0 && safety_words-- > 0)
+ (void)ax_spi_read(xspi, AX_SPI_RXFIFO);
+
+ // Disable all interrupts for this transfer and finalize.
+ ax_spi_write(xspi, AX_SPI_IMR, 0x00);
+ spi_finalize_current_transfer(ctlr);
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * ax_spi_irq - Interrupt service routine of the SPI controller
+ * @irq: IRQ number
+ * @dev_id: Pointer to the xspi structure
+ *
+ * This function handles RX FIFO almost full and Host Transfer Completed interrupts only.
+ * On RX FIFO amlost full interrupt this function reads the received data from RX FIFO and
+ * fills the TX FIFO if there is any data remaining to be transferred.
+ * On Host Transfer Completed interrupt this function indicates that transfer is completed,
+ * the SPI subsystem will clear MTC bit.
+ *
+ * Return: IRQ_HANDLED when handled; IRQ_NONE otherwise.
+ */
+static irqreturn_t ax_spi_irq(int irq, void *dev_id)
+{
+ struct spi_controller *ctlr = dev_id;
+ struct ax_spi *xspi = spi_controller_get_devdata(ctlr);
+ irqreturn_t status;
+ u32 intr_status;
+
+ status = IRQ_NONE;
+ intr_status = ax_spi_read(xspi, AX_SPI_IVR);
+ if (!intr_status)
+ return IRQ_NONE;
+
+ /*
+ * Handle "Message Transfer Complete" interrupt.
+ * This means all bytes have been shifted out of the TX FIFO.
+ * It's time to harvest the final incoming bytes from the RX FIFO.
+ */
+ if (intr_status & AX_SPI_IVR_MTCV) {
+ // Clear the MTC interrupt flag immediately.
+ ax_spi_write(xspi, AX_SPI_ISR, AX_SPI_ISR_MTC);
+
+ // For a TX-only transfer, rx_buf would be NULL.
+ // In the spi-core, rx_copy_remaining would be 0.
+ // So we can finalize immediately.
+ if (!xspi->rx_buf) {
+ ax_spi_write(xspi, AX_SPI_IMR, 0x00);
+ spi_finalize_current_transfer(ctlr);
+ return IRQ_HANDLED;
+ }
+
+ // For a full-duplex transfer, process any remaining RX data.
+ // The helper function will handle finalization if everything is received.
+ ax_spi_process_rx_and_finalize(ctlr);
+ return IRQ_HANDLED;
+ }
+
+ /*
+ * Handle "RX FIFO Full / Threshold Met" interrupt.
+ * This means we need to make space in the RX FIFO by reading from it.
+ */
+ if (intr_status & AX_SPI_IVR_RFFV) {
+ if (ax_spi_process_rx_and_finalize(ctlr)) {
+ // Transfer was finalized inside the helper, we are done.
+ } else {
+ // RX is not yet complete. If there are still TX bytes to send
+ // (for very long transfers), we can fill the TX FIFO again.
+ if (xspi->tx_bytes)
+ ax_spi_fill_tx_fifo(xspi);
+ }
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+static int ax_prepare_message(struct spi_controller *ctlr,
+ struct spi_message *msg)
+{
+ ax_spi_config_clock_mode(msg->spi);
+ return 0;
+}
+
+/**
+ * ax_transfer_one - Initiates the SPI transfer
+ * @ctlr: Pointer to spi_controller structure
+ * @spi: Pointer to the spi_device structure
+ * @transfer: Pointer to the spi_transfer structure which provides
+ * information about next transfer parameters
+ *
+ * This function fills the TX FIFO, starts the SPI transfer and
+ * returns a positive transfer count so that core will wait for completion.
+ *
+ * Return: Number of bytes transferred in the last transfer
+ */
+static int ax_transfer_one(struct spi_controller *ctlr,
+ struct spi_device *spi,
+ struct spi_transfer *transfer)
+{
+ struct ax_spi *xspi = spi_controller_get_devdata(ctlr);
+ int drain_limit;
+
+ /*
+ * Pre-transfer cleanup:Flush the RX FIFO to discard any stale data.
+ * This is the crucial part. Before every new transfer, we must ensure
+ * the HW is in a clean state to avoid processing stale data
+ * from a previous, possibly failed or interrupted, transfer.
+ */
+ drain_limit = AX_SPI_RX_FIFO_DRAIN_LIMIT; // Sane limit to prevent infinite loop on HW error
+ while (ax_spi_read(xspi, AX_SPI_RX_FBCAR) > 0 && drain_limit-- > 0)
+ (void)ax_spi_read(xspi, AX_SPI_RXFIFO); // Read and discard
+
+ if (drain_limit <= 0)
+ dev_warn(&ctlr->dev, "RX FIFO drain timeout before transfer\n");
+
+ /* Clear any stale interrupt flags from a previous transfer.
+ * This prevents an immediate, false interrupt trigger.
+ */
+ ax_spi_write(xspi, AX_SPI_ISR, AX_SPI_ISR_CLR);
+
+ xspi->tx_buf = transfer->tx_buf;
+ xspi->rx_buf = transfer->rx_buf;
+ xspi->tx_bytes = transfer->len;
+ xspi->rx_bytes = transfer->len;
+
+ /* Reset RX 32-bit to byte buffer for each new transfer */
+ if (transfer->tx_buf && !transfer->rx_buf) {
+ /* TX mode: discard all received data */
+ xspi->rx_discard = transfer->len;
+ xspi->rx_copy_remaining = 0;
+ } else if ((!transfer->tx_buf && transfer->rx_buf) ||
+ (transfer->tx_buf && transfer->rx_buf)) {
+ /* RX mode: generate clock by filling TX FIFO with dummy bytes
+ * Full-duplex mode: generate clock by filling TX FIFO
+ */
+ xspi->rx_discard = 0;
+ xspi->rx_copy_remaining = transfer->len;
+ } else {
+ /* No TX and RX */
+ xspi->rx_discard = 0;
+ xspi->rx_copy_remaining = transfer->len;
+ }
+
+ ax_spi_setup_transfer(spi, transfer);
+ ax_spi_fill_tx_fifo(xspi);
+ ax_spi_write(xspi, AX_SPI_CR2, (AX_SPI_CR2_HTE | AX_SPI_CR2_SRD | AX_SPI_CR2_SWD));
+
+ spi_transfer_delay_exec(transfer);
+
+ ax_spi_write(xspi, AX_SPI_IMR, (AX_SPI_IMR_MTCM | AX_SPI_IMR_RFFM));
+ return transfer->len;
+}
+
+/**
+ * ax_prepare_transfer_hardware - Prepares hardware for transfer.
+ * @ctlr: Pointer to the spi_controller structure which provides
+ * information about the controller.
+ *
+ * This function enables SPI host controller.
+ *
+ * Return: 0 always
+ */
+static int ax_prepare_transfer_hardware(struct spi_controller *ctlr)
+{
+ struct ax_spi *xspi = spi_controller_get_devdata(ctlr);
+
+ u32 reg_value;
+
+ reg_value = ax_spi_read(xspi, AX_SPI_CR1);
+ reg_value |= AX_SPI_CR1_SCE;
+
+ ax_spi_write(xspi, AX_SPI_CR1, reg_value);
+
+ return 0;
+}
+
+/**
+ * ax_unprepare_transfer_hardware - Relaxes hardware after transfer
+ * @ctlr: Pointer to the spi_controller structure which provides
+ * information about the controller.
+ *
+ * This function disables the SPI host controller when no target selected.
+ *
+ * Return: 0 always
+ */
+static int ax_unprepare_transfer_hardware(struct spi_controller *ctlr)
+{
+ struct ax_spi *xspi = spi_controller_get_devdata(ctlr);
+
+ u32 reg_value;
+
+ /* Disable the SPI if target is deselected */
+ reg_value = ax_spi_read(xspi, AX_SPI_CR1);
+ reg_value &= ~AX_SPI_CR1_SCE;
+
+ ax_spi_write(xspi, AX_SPI_CR1, reg_value);
+
+ return 0;
+}
+
+/**
+ * ax_spi_detect_fifo_depth - Detect the FIFO depth of the hardware
+ * @xspi: Pointer to the ax_spi structure
+ *
+ * The depth of the TX FIFO is a synthesis configuration parameter of the SPI
+ * IP. The FIFO threshold register is sized so that its maximum value can be the
+ * FIFO size - 1. This is used to detect the size of the FIFO.
+ */
+static void ax_spi_detect_fifo_depth(struct ax_spi *xspi)
+{
+ /* The MSBs will get truncated giving us the size of the FIFO */
+ ax_spi_write(xspi, AX_SPI_TX_FAETR, ALMOST_EMPTY_TRESHOLD);
+ xspi->tx_fifo_depth = FIFO_DEPTH;
+
+ /* Set the threshold limit */
+ ax_spi_write(xspi, AX_SPI_TX_FAETR, ALMOST_EMPTY_TRESHOLD);
+ ax_spi_write(xspi, AX_SPI_RX_FAFTR, ALMOST_FULL_TRESHOLD);
+}
+
+/* --- Internal Helper Function for 32-bit RX FIFO Read --- */
+/**
+ * ax_spi_get_rx_byte - Gets a byte from the RX FIFO buffer
+ * @xspi: Controller private data (struct ax_spi *)
+ *
+ * This function handles the logic of extracting bytes from the 32-bit RX FIFO.
+ * It reads a new 32-bit word from AX_SPI_RXFIFO only when the current buffered
+ * word has been fully processed (all 4 bytes extracted). It then extracts
+ * bytes one by one, assuming the controller is little-endian.
+ *
+ * Returns: The next 8-bit byte read from the RX FIFO stream.
+ */
+static u8 ax_spi_get_rx_byte(struct ax_spi *xspi)
+{
+ u8 byte_val;
+
+ /* If all bytes from the current 32-bit word have been extracted,
+ * read a new word from the hardware RX FIFO.
+ */
+ if (xspi->bytes_left_in_current_rx_word == 0) {
+ xspi->current_rx_fifo_word = ax_spi_read(xspi, AX_SPI_RXFIFO);
+ xspi->bytes_left_in_current_rx_word = 4; // A new 32-bit word has 4 bytes
+ }
+
+ /* Extract the least significant byte from the current 32-bit word */
+ byte_val = (u8)(xspi->current_rx_fifo_word & 0xFF);
+
+ /* Shift the word right by 8 bits to prepare the next byte for extraction */
+ xspi->current_rx_fifo_word >>= 8;
+ xspi->bytes_left_in_current_rx_word--;
+
+ return byte_val;
+}
+
+static int ax_spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
+{
+ struct spi_device *spi = mem->spi;
+ struct ax_spi *xspi = spi_controller_get_devdata(spi->controller);
+ u32 reg_val;
+ int ret = 0;
+ u8 cmd_buf[AX_SPI_COMMAND_BUFFER_SIZE];
+ int cmd_len = 0;
+ int i = 0, timeout = AX_SPI_TRX_FIFO_TIMEOUT;
+ int bytes_to_discard_from_rx;
+ u8 *rx_buf_ptr = (u8 *)op->data.buf.in;
+ u8 *tx_buf_ptr = (u8 *)op->data.buf.out;
+ u32 rx_count_reg = 0;
+
+ dev_dbg(&spi->dev,
+ "%s: cmd:%02x mode:%d.%d.%d.%d addr:%llx len:%d\n",
+ __func__, op->cmd.opcode, op->cmd.buswidth, op->addr.buswidth,
+ op->dummy.buswidth, op->data.buswidth, op->addr.val,
+ op->data.nbytes);
+
+ /* Validate operation parameters: Only 1-bit bus width supported */
+ if (op->cmd.buswidth != 1 ||
+ (op->addr.nbytes && op->addr.buswidth != 0 &&
+ op->addr.buswidth != 1) ||
+ (op->dummy.nbytes && op->dummy.buswidth != 0 &&
+ op->dummy.buswidth != 1) ||
+ (op->data.nbytes && op->data.buswidth != 1)) {
+ dev_err(&spi->dev, "Unsupported bus width, only 1-bit bus width supported\n");
+ return -EOPNOTSUPP;
+ }
+
+ /* Initialize controller hardware */
+ ax_spi_init_hw(xspi);
+
+ /* Assert chip select (pull low) */
+ ax_spi_chipselect(spi, false);
+
+ /* Build command phase: Copy opcode to cmd_buf */
+ if (op->cmd.nbytes == 2) {
+ cmd_buf[cmd_len++] = (op->cmd.opcode >> 8) & 0xFF;
+ cmd_buf[cmd_len++] = op->cmd.opcode & 0xFF;
+ } else {
+ cmd_buf[cmd_len++] = op->cmd.opcode;
+ }
+
+ /* Put address bytes to cmd_buf */
+ if (op->addr.nbytes) {
+ for (i = op->addr.nbytes - 1; i >= 0; i--) {
+ cmd_buf[cmd_len] = (op->addr.val >> (i * 8)) & 0xFF;
+ cmd_len++;
+ }
+ }
+
+ /* Configure controller for desired operation mode (write/read) */
+ reg_val = ax_spi_read(xspi, AX_SPI_CR2);
+ reg_val |= AX_SPI_CR2_SWD | AX_SPI_CR2_SRI | AX_SPI_CR2_SRD;
+ ax_spi_write(xspi, AX_SPI_CR2, reg_val);
+
+ /* Write command and address bytes to TX_FIFO */
+ for (i = 0; i < cmd_len; i++)
+ ax_spi_write_b(xspi, AX_SPI_TXFIFO, cmd_buf[i]);
+
+ /* Add dummy bytes (for clock generation) or actual data bytes to TX_FIFO */
+ if (op->data.dir == SPI_MEM_DATA_IN) {
+ for (i = 0; i < op->dummy.nbytes; i++)
+ ax_spi_write_b(xspi, AX_SPI_TXFIFO, 0x00);
+ for (i = 0; i < op->data.nbytes; i++)
+ ax_spi_write_b(xspi, AX_SPI_TXFIFO, 0x00);
+ } else {
+ for (i = 0; i < op->data.nbytes; i++)
+ ax_spi_write_b(xspi, AX_SPI_TXFIFO, tx_buf_ptr[i]);
+ }
+
+ /* Start the SPI transmission */
+ reg_val = ax_spi_read(xspi, AX_SPI_CR2);
+ reg_val |= AX_SPI_CR2_HTE;
+ ax_spi_write(xspi, AX_SPI_CR2, reg_val);
+
+ /* Wait for TX FIFO to become empty */
+ while (timeout-- > 0) {
+ u32 tx_count_reg = ax_spi_read(xspi, AX_SPI_TX_FBCAR);
+
+ if (tx_count_reg == 0) {
+ udelay(1);
+ break;
+ }
+ udelay(1);
+ }
+
+ /* Handle Data Reception (for read operations) */
+ if (op->data.dir == SPI_MEM_DATA_IN) {
+ /* Reset the internal RX byte buffer for this new operation.
+ * This ensures ax_spi_get_rx_byte starts fresh for each exec_op call.
+ */
+ xspi->bytes_left_in_current_rx_word = 0;
+ xspi->current_rx_fifo_word = 0;
+
+ timeout = AX_SPI_TRX_FIFO_TIMEOUT;
+ while (timeout-- > 0) {
+ rx_count_reg = ax_spi_read(xspi, AX_SPI_RX_FBCAR);
+ if (rx_count_reg >= op->data.nbytes)
+ break;
+ udelay(1); // Small delay to prevent aggressive busy-waiting
+ }
+
+ if (timeout < 0) {
+ ret = -ETIMEDOUT;
+ goto out_unlock;
+ }
+
+ /* Calculate how many bytes we need to discard from the RX FIFO.
+ * Since we set SRI, we only need to discard the address bytes and
+ * dummy bytes from the RX FIFO.
+ */
+ bytes_to_discard_from_rx = op->addr.nbytes + op->dummy.nbytes;
+ for (i = 0; i < bytes_to_discard_from_rx; i++)
+ ax_spi_get_rx_byte(xspi);
+
+ /* Read actual data bytes into op->data.buf.in */
+ for (i = 0; i < op->data.nbytes; i++) {
+ *rx_buf_ptr = ax_spi_get_rx_byte(xspi);
+ rx_buf_ptr++;
+ }
+ } else if (op->data.dir == SPI_MEM_DATA_OUT) {
+ timeout = AX_SPI_TRX_FIFO_TIMEOUT;
+ while (timeout-- > 0) {
+ u32 tx_fifo_level = ax_spi_read(xspi, AX_SPI_TX_FBCAR);
+
+ if (tx_fifo_level == 0)
+ break;
+ udelay(1);
+ }
+ if (timeout < 0) {
+ ret = -ETIMEDOUT;
+ goto out_unlock;
+ }
+ }
+
+out_unlock:
+ /* Deassert chip select (pull high) */
+ ax_spi_chipselect(spi, true);
+
+ return ret;
+}
+
+static int ax_spi_mem_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
+{
+ struct spi_device *spi = mem->spi;
+ struct ax_spi *xspi = spi_controller_get_devdata(spi->controller);
+ size_t max_transfer_payload_bytes;
+ size_t fifo_total_bytes;
+ size_t protocol_overhead_bytes;
+
+ fifo_total_bytes = xspi->tx_fifo_depth;
+ /* Calculate protocol overhead bytes according to the real operation each time. */
+ protocol_overhead_bytes = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
+
+ /*Calculate the maximum data payload that can fit into the FIFO. */
+ if (fifo_total_bytes <= protocol_overhead_bytes) {
+ max_transfer_payload_bytes = 0;
+ dev_warn_once(&spi->dev, "SPI FIFO (%zu bytes) is too small for protocol overhead (%zu bytes)! Max data size forced to 0.\n",
+ fifo_total_bytes, protocol_overhead_bytes);
+ } else {
+ max_transfer_payload_bytes = fifo_total_bytes - protocol_overhead_bytes;
+ }
+
+ /* Limit op->data.nbytes based on the calculated max payload and SZ_64K.
+ * This is the value that spi-mem will then use to split requests.
+ */
+ if (op->data.nbytes > max_transfer_payload_bytes) {
+ op->data.nbytes = max_transfer_payload_bytes;
+ dev_dbg(&spi->dev, "%s %d: op->data.nbytes adjusted to %u due to FIFO overhead\n",
+ __func__, __LINE__, op->data.nbytes);
+ }
+
+ /* Also apply the overall max transfer size */
+ if (op->data.nbytes > SZ_64K) {
+ op->data.nbytes = SZ_64K;
+ dev_dbg(&spi->dev, "%s %d: op->data.nbytes adjusted to %u due to SZ_64K limit\n",
+ __func__, __LINE__, op->data.nbytes);
+ }
+
+ return 0;
+}
+
+static const struct spi_controller_mem_ops ax_spi_mem_ops = {
+ .exec_op = ax_spi_mem_exec_op,
+ .adjust_op_size = ax_spi_mem_adjust_op_size,
+};
+
+/**
+ * ax_spi_probe - Probe method for the SPI driver
+ * @pdev: Pointer to the platform_device structure
+ *
+ * This function initializes the driver data structures and the hardware.
+ *
+ * Return: 0 on success and error value on error
+ */
+static int ax_spi_probe(struct platform_device *pdev)
+{
+ int ret = 0, irq;
+ struct spi_controller *ctlr;
+ struct ax_spi *xspi;
+ u32 num_cs;
+
+ ctlr = devm_spi_alloc_host(&pdev->dev, sizeof(*xspi));
+ if (!ctlr)
+ return -ENOMEM;
+
+ xspi = spi_controller_get_devdata(ctlr);
+ ctlr->dev.of_node = pdev->dev.of_node;
+ platform_set_drvdata(pdev, ctlr);
+
+ xspi->regs = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(xspi->regs)) {
+ ret = PTR_ERR(xspi->regs);
+ goto remove_ctlr;
+ }
+
+ xspi->pclk = devm_clk_get(&pdev->dev, "pclk");
+ if (IS_ERR(xspi->pclk)) {
+ dev_err(&pdev->dev, "pclk clock not found.\n");
+ ret = PTR_ERR(xspi->pclk);
+ goto remove_ctlr;
+ }
+
+ xspi->ref_clk = devm_clk_get(&pdev->dev, "ref_clk");
+ if (IS_ERR(xspi->ref_clk)) {
+ dev_err(&pdev->dev, "ref_clk clock not found.\n");
+ ret = PTR_ERR(xspi->ref_clk);
+ goto remove_ctlr;
+ }
+
+ ret = clk_prepare_enable(xspi->pclk);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to enable APB clock.\n");
+ goto remove_ctlr;
+ }
+
+ ret = clk_prepare_enable(xspi->ref_clk);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to enable device clock.\n");
+ goto clk_dis_apb;
+ }
+
+ pm_runtime_use_autosuspend(&pdev->dev);
+ pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
+ pm_runtime_get_noresume(&pdev->dev);
+ pm_runtime_set_active(&pdev->dev);
+ pm_runtime_enable(&pdev->dev);
+
+ ret = of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs);
+ if (ret < 0)
+ ctlr->num_chipselect = AX_SPI_DEFAULT_NUM_CS;
+ else
+ ctlr->num_chipselect = num_cs;
+
+ ax_spi_detect_fifo_depth(xspi);
+
+ xspi->current_rx_fifo_word = 0;
+ xspi->bytes_left_in_current_rx_word = 0;
+
+ /* Initialize IRQ-related variables */
+ xspi->bytes_left_in_current_rx_word_for_irq = 0;
+ xspi->current_rx_fifo_word_for_irq = 0;
+
+ /* SPI controller initializations */
+ ax_spi_init_hw(xspi);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq <= 0) {
+ ret = -ENXIO;
+ goto clk_dis_all;
+ }
+
+ ret = devm_request_irq(&pdev->dev, irq, ax_spi_irq,
+ 0, pdev->name, ctlr);
+ if (ret != 0) {
+ ret = -ENXIO;
+ dev_err(&pdev->dev, "request_irq failed\n");
+ goto clk_dis_all;
+ }
+
+ ctlr->use_gpio_descriptors = true;
+ ctlr->prepare_transfer_hardware = ax_prepare_transfer_hardware;
+ ctlr->prepare_message = ax_prepare_message;
+ ctlr->transfer_one = ax_transfer_one;
+ ctlr->unprepare_transfer_hardware = ax_unprepare_transfer_hardware;
+ ctlr->set_cs = ax_spi_chipselect;
+ ctlr->auto_runtime_pm = true;
+ ctlr->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+
+ xspi->clk_rate = clk_get_rate(xspi->ref_clk);
+ /* Set to default valid value */
+ ctlr->max_speed_hz = xspi->clk_rate / 2;
+ xspi->speed_hz = ctlr->max_speed_hz;
+
+ ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
+
+ pm_runtime_mark_last_busy(&pdev->dev);
+ pm_runtime_put_autosuspend(&pdev->dev);
+
+ ctlr->mem_ops = &ax_spi_mem_ops;
+
+ ret = spi_register_controller(ctlr);
+ if (ret) {
+ dev_err(&pdev->dev, "spi_register_controller failed\n");
+ goto clk_dis_all;
+ }
+
+ return ret;
+
+clk_dis_all:
+ pm_runtime_set_suspended(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
+ clk_disable_unprepare(xspi->ref_clk);
+clk_dis_apb:
+ clk_disable_unprepare(xspi->pclk);
+remove_ctlr:
+ spi_controller_put(ctlr);
+ return ret;
+}
+
+/**
+ * ax_spi_remove - Remove method for the SPI driver
+ * @pdev: Pointer to the platform_device structure
+ *
+ * This function is called if a device is physically removed from the system or
+ * if the driver module is being unloaded. It frees all resources allocated to
+ * the device.
+ */
+static void ax_spi_remove(struct platform_device *pdev)
+{
+ struct spi_controller *ctlr = platform_get_drvdata(pdev);
+ struct ax_spi *xspi = spi_controller_get_devdata(ctlr);
+
+ spi_unregister_controller(ctlr);
+
+ pm_runtime_set_suspended(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
+
+ clk_disable_unprepare(xspi->ref_clk);
+ clk_disable_unprepare(xspi->pclk);
+}
+
+/**
+ * ax_spi_suspend - Suspend method for the SPI driver
+ * @dev: Address of the platform_device structure
+ *
+ * This function disables the SPI controller and
+ * changes the driver state to "suspend"
+ *
+ * Return: 0 on success and error value on error
+ */
+static int __maybe_unused ax_spi_suspend(struct device *dev)
+{
+ struct spi_controller *ctlr = dev_get_drvdata(dev);
+
+ return spi_controller_suspend(ctlr);
+}
+
+/**
+ * ax_spi_resume - Resume method for the SPI driver
+ * @dev: Address of the platform_device structure
+ *
+ * This function changes the driver state to "ready"
+ *
+ * Return: 0 on success and error value on error
+ */
+static int __maybe_unused ax_spi_resume(struct device *dev)
+{
+ struct spi_controller *ctlr = dev_get_drvdata(dev);
+ struct ax_spi *xspi = spi_controller_get_devdata(ctlr);
+
+ ax_spi_init_hw(xspi);
+ return spi_controller_resume(ctlr);
+}
+
+/**
+ * ax_spi_runtime_resume - Runtime resume method for the SPI driver
+ * @dev: Address of the platform_device structure
+ *
+ * This function enables the clocks
+ *
+ * Return: 0 on success and error value on error
+ */
+static int __maybe_unused ax_spi_runtime_resume(struct device *dev)
+{
+ struct spi_controller *ctlr = dev_get_drvdata(dev);
+ struct ax_spi *xspi = spi_controller_get_devdata(ctlr);
+ int ret;
+
+ ret = clk_prepare_enable(xspi->pclk);
+ if (ret) {
+ dev_err(dev, "Cannot enable APB clock.\n");
+ return ret;
+ }
+
+ ret = clk_prepare_enable(xspi->ref_clk);
+ if (ret) {
+ dev_err(dev, "Cannot enable device clock.\n");
+ clk_disable_unprepare(xspi->pclk);
+ return ret;
+ }
+ return 0;
+}
+
+/**
+ * ax_spi_runtime_suspend - Runtime suspend method for the SPI driver
+ * @dev: Address of the platform_device structure
+ *
+ * This function disables the clocks
+ *
+ * Return: Always 0
+ */
+static int __maybe_unused ax_spi_runtime_suspend(struct device *dev)
+{
+ struct spi_controller *ctlr = dev_get_drvdata(dev);
+ struct ax_spi *xspi = spi_controller_get_devdata(ctlr);
+
+ clk_disable_unprepare(xspi->ref_clk);
+ clk_disable_unprepare(xspi->pclk);
+
+ return 0;
+}
+
+static const struct dev_pm_ops ax_spi_dev_pm_ops = {
+ SET_RUNTIME_PM_OPS(ax_spi_runtime_suspend,
+ ax_spi_runtime_resume, NULL)
+ SET_SYSTEM_SLEEP_PM_OPS(ax_spi_suspend, ax_spi_resume)
+};
+
+static const struct of_device_id ax_spi_of_match[] = {
+ { .compatible = "axiado,ax3000-spi" },
+ { /* end of table */ }
+};
+MODULE_DEVICE_TABLE(of, ax_spi_of_match);
+
+/* ax_spi_driver - This structure defines the SPI subsystem platform driver */
+static struct platform_driver ax_spi_driver = {
+ .probe = ax_spi_probe,
+ .remove = ax_spi_remove,
+ .driver = {
+ .name = AX_SPI_NAME,
+ .of_match_table = ax_spi_of_match,
+ .pm = &ax_spi_dev_pm_ops,
+ },
+};
+
+module_platform_driver(ax_spi_driver);
+
+MODULE_AUTHOR("Axiado Corporation");
+MODULE_DESCRIPTION("Axiado SPI Host driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/spi/spi-axiado.h b/drivers/spi/spi-axiado.h
new file mode 100644
index 0000000000000000000000000000000000000000..3d0a1437bd32e5a59937a1b68cdbd741ca254716
--- /dev/null
+++ b/drivers/spi/spi-axiado.h
@@ -0,0 +1,129 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Axiado SPI controller driver (Host mode only)
+ *
+ * Copyright (C) 2022-2025 Axiado Corporation (or its affiliates). All rights reserved.
+ */
+
+/* Name of this driver */
+#define AX_SPI_NAME "axiado-db-spi"
+
+/* Axiado - SPI Digital Blocks IP design registers */
+#define AX_SPI_TX_FAETR 0x18 // TX-FAETR
+#define ALMOST_EMPTY_TRESHOLD 0x00 // Programmed threshold value
+#define AX_SPI_RX_FAFTR 0x28 // RX-FAETR
+#define ALMOST_FULL_TRESHOLD 0x0c // Programmed threshold value
+#define FIFO_DEPTH 256 // 256 bytes
+
+#define AX_SPI_CR1 0x00 // CR1
+#define AX_SPI_CR1_CLR 0x00 // CR1 - Clear
+#define AX_SPI_CR1_SCR 0x01 // CR1 - controller reset
+#define AX_SPI_CR1_SCE 0x02 // CR1 - Controller Enable/Disable
+#define AX_SPI_CR1_CPHA 0x08 // CR1 - CPH
+#define AX_SPI_CR1_CPOL 0x10 // CR1 - CPO
+
+#define AX_SPI_CR2 0x04 // CR2
+#define AX_SPI_CR2_SWD 0x04 // CR2 - Write Enabel/Disable
+#define AX_SPI_CR2_SRD 0x08 // CR2 - Read Enable/Disable
+#define AX_SPI_CR2_SRI 0x10 // CR2 - Read First Byte Ignore
+#define AX_SPI_CR2_HTE 0x40 // CR2 - Host Transmit Enable
+#define AX_SPI_CR3 0x08 // CR3
+#define AX_SPI_CR3_SDL 0x00 // CR3 - Data lines
+#define AX_SPI_CR3_QUAD 0x02 // CR3 - Data lines
+
+/* As per Digital Blocks datasheet clock frequency range
+ * Min - 244KHz
+ * Max - 62.5MHz
+ * SCK Clock Divider Register Values
+ */
+#define AX_SPI_RX_FBCAR 0x24 // RX_FBCAR
+#define AX_SPI_TX_FBCAR 0x14 // TX_FBCAR
+#define AX_SPI_SCDR 0x2c // SCDR
+#define AX_SPI_SCD_MIN 0x1fe // Valid SCD (SCK Clock Divider Register)
+#define AX_SPI_SCD_DEFAULT 0x06 // Default SCD (SCK Clock Divider Register)
+#define AX_SPI_SCD_MAX 0x00 // Valid SCD (SCK Clock Divider Register)
+#define AX_SPI_SCDR_SCS 0x0200 // SCDR - AMBA Bus Clock source
+
+#define AX_SPI_IMR 0x34 // IMR
+#define AX_SPI_IMR_CLR 0x00 // IMR - Clear
+#define AX_SPI_IMR_TFOM 0x02 // IMR - TFO
+#define AX_SPI_IMR_MTCM 0x40 // IMR - MTC
+#define AX_SPI_IMR_TFEM 0x10 // IMR - TFE
+#define AX_SPI_IMR_RFFM 0x20 // IMR - RFFM
+
+#define AX_SPI_ISR 0x30 // ISR
+#define AX_SPI_ISR_CLR 0xff // ISR - Clear
+#define AX_SPI_ISR_MTC 0x40 // ISR - MTC
+#define AX_SPI_ISR_TFE 0x10 // ISR - TFE
+#define AX_SPI_ISR_RFF 0x20 // ISR - RFF
+
+#define AX_SPI_IVR 0x38 // IVR
+#define AX_SPI_IVR_TFOV 0x02 // IVR - TFOV
+#define AX_SPI_IVR_MTCV 0x40 // IVR - MTCV
+#define AX_SPI_IVR_TFEV 0x10 // IVR - TFEV
+#define AX_SPI_IVR_RFFV 0x20 // IVR - RFFV
+
+#define AX_SPI_TXFIFO 0x0c // TX_FIFO
+#define AX_SPI_TX_RX_FBCR 0x10 // TX_RX_FBCR
+#define AX_SPI_RXFIFO 0x1c // RX_FIFO
+
+#define AX_SPI_TS0 0x00 // Target select 0
+#define AX_SPI_TS1 0x01 // Target select 1
+#define AX_SPI_TS2 0x10 // Target select 2
+#define AX_SPI_TS3 0x11 // Target select 3
+
+#define SPI_AUTOSUSPEND_TIMEOUT 3000
+
+/* Default number of chip select lines also used as maximum number of chip select lines */
+#define AX_SPI_DEFAULT_NUM_CS 4
+
+/* Default number of command buffer size */
+#define AX_SPI_COMMAND_BUFFER_SIZE 16 //Command + address bytes
+
+/* Target select mask
+ * 00 – TS0
+ * 01 – TS1
+ * 10 – TS2
+ * 11 – TS3
+ */
+#define AX_SPI_DEFAULT_TS_MASK 0x03
+
+#define AX_SPI_RX_FIFO_DRAIN_LIMIT 24
+#define AX_SPI_TRX_FIFO_TIMEOUT 1000
+/**
+ * struct ax_spi - This definition defines spi driver instance
+ * @regs: Virtual address of the SPI controller registers
+ * @ref_clk: Pointer to the peripheral clock
+ * @pclk: Pointer to the APB clock
+ * @speed_hz: Current SPI bus clock speed in Hz
+ * @txbuf: Pointer to the TX buffer
+ * @rxbuf: Pointer to the RX buffer
+ * @tx_bytes: Number of bytes left to transfer
+ * @rx_bytes: Number of bytes requested
+ * @tx_fifo_depth: Depth of the TX FIFO
+ * @current_rx_fifo_word: Buffers the 32-bit word read from RXFIFO
+ * @bytes_left_in_current_rx_word: Bytes to be extracted from current 32-bit word
+ * @current_rx_fifo_word_for_irq: Buffers the 32-bit word read from RXFIFO for IRQ
+ * @bytes_left_in_current_rx_word_for_irq: IRQ bytes to be extracted from current 32-bit word
+ * @rx_discard: Number of bytes to discard
+ * @rx_copy_remaining: Number of bytes to copy
+ */
+struct ax_spi {
+ void __iomem *regs;
+ struct clk *ref_clk;
+ struct clk *pclk;
+ unsigned int clk_rate;
+ u32 speed_hz;
+ const u8 *tx_buf;
+ u8 *rx_buf;
+ int tx_bytes;
+ int rx_bytes;
+ unsigned int tx_fifo_depth;
+ u32 current_rx_fifo_word;
+ int bytes_left_in_current_rx_word;
+ u32 current_rx_fifo_word_for_irq;
+ int bytes_left_in_current_rx_word_for_irq;
+ int rx_discard;
+ int rx_copy_remaining;
+};
+

--
2.25.1