[RFC PATCH 1/5] spi: Add support for Zynq qspi controller

Naga Sureshkumar Relli
2018-03-23T12:23:48Z

This patch adds support for QSPI controller driver used by
Xilinx Zynq SOC.

Signed-off-by: Naga Sureshkumar Relli <nagasure@xilinx.com>
---
drivers/spi/Kconfig | 15 +
drivers/spi/Makefile | 1 +
drivers/spi/spi-zynq-qspi.c | 769 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 785 insertions(+)
create mode 100644 drivers/spi/spi-zynq-qspi.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 6037839..75b8f13 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -762,6 +762,21 @@ config SPI_ZYNQMP_GQSPI
help
Enables Xilinx GQSPI controller driver for Zynq UltraScale+ MPSoC.

+config SPI_ZYNQ_QSPI
+ tristate "Xilinx Zynq QSPI controller"
+ depends on ARCH_ZYNQ
+ depends on SPI_MASTER
+ help
+ This selects the Xilinx ZYNQ Quad SPI controller master driver.
+
+config SPI_ZYNQ_QSPI_DUAL_STACKED
+ bool "Xilinx Zynq QSPI Dual stacked configuration"
+ depends on SPI_ZYNQ_QSPI
+ help
+ This selects the Xilinx ZYNQ Quad SPI controller in dual stacked mode.
+ Enable this option if your hw design is using dual stacked
+ configuration.
+
#
# Add new SPI master controllers in alphabetical order above this line
#
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 34c5f28..b49cff6 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -109,6 +109,7 @@ obj-$(CONFIG_SPI_XILINX) += spi-xilinx.o
obj-$(CONFIG_SPI_XLP) += spi-xlp.o
obj-$(CONFIG_SPI_XTENSA_XTFPGA) += spi-xtensa-xtfpga.o
obj-$(CONFIG_SPI_ZYNQMP_GQSPI) += spi-zynqmp-gqspi.o
+obj-$(CONFIG_SPI_ZYNQ_QSPI) += spi-zynq-qspi.o

# SPI slave protocol handlers
obj-$(CONFIG_SPI_SLAVE_TIME) += spi-slave-time.o
diff --git a/drivers/spi/spi-zynq-qspi.c b/drivers/spi/spi-zynq-qspi.c
new file mode 100644
index 0000000..7a772ca
--- /dev/null
+++ b/drivers/spi/spi-zynq-qspi.c
@@ -0,0 +1,769 @@
+
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Xilinx Zynq Quad-SPI (QSPI) controller driver (master mode only)
+ *
+ * Copyright (C) 2017 Xilinx, Inc.
+ * Author: harini katakam <harinik@xilinx.com>
+ * Author: nagasuresh <nagasure@xilinx.com>
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.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/spi/spi.h>
+#include <linux/workqueue.h>
+
+/* Name of this driver */
+#define DRIVER_NAME "zynq-qspi"
+
+/* Register offset definitions */
+#define ZYNQ_QSPI_CONFIG_OFFSET 0x00 /* Configuration Register, RW */
+#define ZYNQ_QSPI_STATUS_OFFSET 0x04 /* Interrupt Status Register, RO */
+#define ZYNQ_QSPI_IEN_OFFSET 0x08 /* Interrupt Enable Register, WO */
+#define ZYNQ_QSPI_IDIS_OFFSET 0x0C /* Interrupt Disable Reg, WO */
+#define ZYNQ_QSPI_IMASK_OFFSET 0x10 /* Interrupt Enabled Mask Reg,RO */
+#define ZYNQ_QSPI_ENABLE_OFFSET 0x14 /* Enable/Disable Register, RW */
+#define ZYNQ_QSPI_DELAY_OFFSET 0x18 /* Delay Register, RW */
+#define ZYNQ_QSPI_TXD_00_00_OFFSET 0x1C /* Transmit 4-byte inst, WO */
+#define ZYNQ_QSPI_TXD_00_01_OFFSET 0x80 /* Transmit 1-byte inst, WO */
+#define ZYNQ_QSPI_TXD_00_10_OFFSET 0x84 /* Transmit 2-byte inst, WO */
+#define ZYNQ_QSPI_TXD_00_11_OFFSET 0x88 /* Transmit 3-byte inst, WO */
+#define ZYNQ_QSPI_RXD_OFFSET 0x20 /* Data Receive Register, RO */
+#define ZYNQ_QSPI_SIC_OFFSET 0x24 /* Slave Idle Count Register, RW */
+#define ZYNQ_QSPI_TX_THRESH_OFFSET 0x28 /* TX FIFO Watermark Reg, RW */
+#define ZYNQ_QSPI_RX_THRESH_OFFSET 0x2C /* RX FIFO Watermark Reg, RW */
+#define ZYNQ_QSPI_GPIO_OFFSET 0x30 /* GPIO Register, RW */
+#define ZYNQ_QSPI_LINEAR_CFG_OFFSET 0xA0 /* Linear Adapter Config Ref, RW */
+#define ZYNQ_QSPI_MOD_ID_OFFSET 0xFC /* Module ID Register, RO */
+
+/*
+ * QSPI Configuration Register bit Masks
+ *
+ * This register contains various control bits that effect the operation
+ * of the QSPI controller
+ */
+#define ZYNQ_QSPI_CONFIG_IFMODE_MASK 0x80000000 /* Flash Memory Interface */
+#define ZYNQ_QSPI_CONFIG_MANSRT_MASK 0x00010000 /* Manual TX Start */
+#define ZYNQ_QSPI_CONFIG_MANSRTEN_MASK 0x00008000 /* Enable Manual TX Mode */
+#define ZYNQ_QSPI_CONFIG_SSFORCE_MASK 0x00004000 /* Manual Chip Select */
+#define ZYNQ_QSPI_CONFIG_BDRATE_MASK 0x00000038 /* Baud Rate Divisor Mask */
+#define ZYNQ_QSPI_CONFIG_CPHA_MASK 0x00000004 /* Clock Phase Control */
+#define ZYNQ_QSPI_CONFIG_CPOL_MASK 0x00000002 /* Clock Polarity Control */
+#define ZYNQ_QSPI_CONFIG_SSCTRL_MASK 0x00003C00 /* Slave Select Mask */
+#define ZYNQ_QSPI_CONFIG_FWIDTH_MASK 0x000000C0 /* FIFO width */
+#define ZYNQ_QSPI_CONFIG_MSTREN_MASK 0x00000001 /* Master Mode */
+
+/*
+ * QSPI Configuration Register - Baud rate and slave select
+ *
+ * These are the values used in the calculation of baud rate divisor and
+ * setting the slave select.
+ */
+#define ZYNQ_QSPI_BAUD_DIV_MAX 7 /* Baud rate divisor maximum */
+#define ZYNQ_QSPI_BAUD_DIV_SHIFT 3 /* Baud rate divisor shift in CR */
+#define ZYNQ_QSPI_SS_SHIFT 10 /* Slave Select field shift in CR */
+
+/*
+ * QSPI Interrupt Registers bit Masks
+ *
+ * All the four interrupt registers (Status/Mask/Enable/Disable) have the same
+ * bit definitions.
+ */
+#define ZYNQ_QSPI_IXR_TXNFULL_MASK 0x00000004 /* QSPI TX FIFO Overflow */
+#define ZYNQ_QSPI_IXR_TXFULL_MASK 0x00000008 /* QSPI TX FIFO is full */
+#define ZYNQ_QSPI_IXR_RXNEMTY_MASK 0x00000010 /* QSPI RX FIFO Not Empty */
+#define ZYNQ_QSPI_IXR_ALL_MASK (ZYNQ_QSPI_IXR_TXNFULL_MASK | \
+ ZYNQ_QSPI_IXR_RXNEMTY_MASK)
+
+/*
+ * QSPI Enable Register bit Masks
+ *
+ * This register is used to enable or disable the QSPI controller
+ */
+#define ZYNQ_QSPI_ENABLE_ENABLE_MASK 0x00000001 /* QSPI Enable Bit Mask */
+
+/*
+ * QSPI Linear Configuration Register
+ *
+ * It is named Linear Configuration but it controls other modes when not in
+ * linear mode also.
+ */
+#define ZYNQ_QSPI_LCFG_TWO_MEM_MASK 0x40000000 /* LQSPI Two memories Mask */
+#define ZYNQ_QSPI_LCFG_SEP_BUS_MASK 0x20000000 /* LQSPI Separate bus Mask */
+#define ZYNQ_QSPI_LCFG_U_PAGE_MASK 0x10000000 /* LQSPI Upper Page Mask */
+
+#define ZYNQ_QSPI_LCFG_DUMMY_SHIFT 8
+
+#define ZYNQ_QSPI_FAST_READ_QOUT_CODE 0x6B /* read instruction code */
+#define ZYNQ_QSPI_FIFO_DEPTH 63 /* FIFO depth in words */
+#define ZYNQ_QSPI_RX_THRESHOLD 32 /* Rx FIFO threshold level */
+#define ZYNQ_QSPI_TX_THRESHOLD 1 /* Tx FIFO threshold level */
+
+/*
+ * The modebits configurable by the driver to make the SPI support different
+ * data formats
+ */
+#define MODEBITS (SPI_CPOL | SPI_CPHA)
+
+/* Default number of chip selects */
+#define ZYNQ_QSPI_DEFAULT_NUM_CS 1
+
+/**
+ * struct zynq_qspi - Defines qspi driver instance
+ * @regs: Virtual address of the QSPI controller registers
+ * @refclk: Pointer to the peripheral clock
+ * @pclk: Pointer to the APB clock
+ * @irq: IRQ number
+ * @txbuf: Pointer to the TX buffer
+ * @rxbuf: Pointer to the RX buffer
+ * @bytes_to_transfer: Number of bytes left to transfer
+ * @bytes_to_receive: Number of bytes left to receive
+ * @is_dual: Flag to indicate whether dual flash memories are used
+ * @is_instr: Flag to indicate if transfer contains an instruction
+ * (Used in dual parallel configuration)
+ */
+struct zynq_qspi {
+ void __iomem *regs;
+ struct clk *refclk;
+ struct clk *pclk;
+ int irq;
+ const void *txbuf;
+ void *rxbuf;
+ int bytes_to_transfer;
+ int bytes_to_receive;
+ u32 is_dual;
+ u8 is_instr;
+};
+
+/*
+ * Inline functions for the QSPI controller read/write
+ */
+static inline u32 zynq_qspi_read(struct zynq_qspi *xqspi, u32 offset)
+{
+ return readl_relaxed(xqspi->regs + offset);
+}
+
+static inline void zynq_qspi_write(struct zynq_qspi *xqspi, u32 offset,
+ u32 val)
+{
+ writel_relaxed(val, xqspi->regs + offset);
+}
+
+/**
+ * zynq_qspi_init_hw - Initialize the hardware
+ * @xqspi: Pointer to the zynq_qspi structure
+ *
+ * The default settings of the QSPI controller's configurable parameters on
+ * reset are
+ * - Master mode
+ * - Baud rate divisor is set to 2
+ * - Tx threshold set to 1l Rx threshold set to 32
+ * - Flash memory interface mode enabled
+ * - Size of the word to be transferred as 8 bit
+ * This function performs the following actions
+ * - Disable and clear all the interrupts
+ * - Enable manual slave select
+ * - Enable manual start
+ * - Deselect all the chip select lines
+ * - Set the size of the word to be transferred as 32 bit
+ * - Set the little endian mode of TX FIFO and
+ * - Enable the QSPI controller
+ */
+static void zynq_qspi_init_hw(struct zynq_qspi *xqspi)
+{
+ u32 config_reg;
+
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET, 0);
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_IDIS_OFFSET, 0x7F);
+
+ /* Disable linear mode as the boot loader may have used it */
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_LINEAR_CFG_OFFSET, 0);
+
+ /* Clear the RX FIFO */
+ while (zynq_qspi_read(xqspi, ZYNQ_QSPI_STATUS_OFFSET) &
+ ZYNQ_QSPI_IXR_RXNEMTY_MASK)
+ zynq_qspi_read(xqspi, ZYNQ_QSPI_RXD_OFFSET);
+
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_STATUS_OFFSET, 0x7F);
+ config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_CONFIG_OFFSET);
+ config_reg &= ~(ZYNQ_QSPI_CONFIG_MSTREN_MASK |
+ ZYNQ_QSPI_CONFIG_CPOL_MASK |
+ ZYNQ_QSPI_CONFIG_CPHA_MASK |
+ ZYNQ_QSPI_CONFIG_BDRATE_MASK |
+ ZYNQ_QSPI_CONFIG_SSFORCE_MASK |
+ ZYNQ_QSPI_CONFIG_MANSRTEN_MASK |
+ ZYNQ_QSPI_CONFIG_MANSRT_MASK);
+ config_reg |= (ZYNQ_QSPI_CONFIG_MSTREN_MASK |
+ ZYNQ_QSPI_CONFIG_SSFORCE_MASK |
+ ZYNQ_QSPI_CONFIG_FWIDTH_MASK |
+ ZYNQ_QSPI_CONFIG_IFMODE_MASK);
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_CONFIG_OFFSET, config_reg);
+
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_RX_THRESH_OFFSET,
+ ZYNQ_QSPI_RX_THRESHOLD);
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_TX_THRESH_OFFSET,
+ ZYNQ_QSPI_TX_THRESHOLD);
+
+ if (xqspi->is_dual)
+ /* Enable two memories on separate buses */
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_LINEAR_CFG_OFFSET,
+ (ZYNQ_QSPI_LCFG_TWO_MEM_MASK |
+ ZYNQ_QSPI_LCFG_SEP_BUS_MASK |
+ (1 << ZYNQ_QSPI_LCFG_DUMMY_SHIFT) |
+ ZYNQ_QSPI_FAST_READ_QOUT_CODE));
+#ifdef CONFIG_SPI_ZYNQ_QSPI_DUAL_STACKED
+ /* Enable two memories on shared bus */
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_LINEAR_CFG_OFFSET,
+ (ZYNQ_QSPI_LCFG_TWO_MEM_MASK |
+ (1 << ZYNQ_QSPI_LCFG_DUMMY_SHIFT) |
+ ZYNQ_QSPI_FAST_READ_QOUT_CODE));
+#endif
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET,
+ ZYNQ_QSPI_ENABLE_ENABLE_MASK);
+}
+
+/**
+ * zynq_qspi_read_rx_fifo - Read 1..4 bytes from RxFIFO to RX buffer
+ * @xqspi: Pointer to the zynq_qspi structure
+ * @size: Number of bytes to be read (1..4)
+ *
+ * Note: In case of dual parallel connection, even number of bytes are read
+ * when odd bytes are requested to avoid transfer of a nibble to each flash.
+ * The receive buffer though, is populated with the number of bytes requested.
+ */
+static void zynq_qspi_read_rx_fifo(struct zynq_qspi *xqspi, unsigned int size)
+{
+ unsigned int xsize;
+ u32 data;
+
+ data = zynq_qspi_read(xqspi, ZYNQ_QSPI_RXD_OFFSET);
+
+ if (xqspi->rxbuf) {
+ xsize = size;
+ if (xqspi->is_dual && !xqspi->is_instr && (size % 2))
+ xsize++;
+ memcpy(xqspi->rxbuf, ((u8 *)&data) + 4 - xsize, size);
+ xqspi->rxbuf += size;
+ }
+
+ xqspi->bytes_to_receive -= size;
+ if (xqspi->bytes_to_receive < 0)
+ xqspi->bytes_to_receive = 0;
+}
+
+/**
+ * zynq_qspi_write_tx_fifo - Write 1..4 bytes from TX buffer to TxFIFO
+ * @xqspi: Pointer to the zynq_qspi structure
+ * @size: Number of bytes to be written (1..4)
+ *
+ * In dual parallel configuration, when read/write data operations
+ * are performed, odd data bytes have to be converted to even to
+ * avoid a nibble (of data when programming / dummy when reading)
+ * going to individual flash devices, where a byte is expected.
+ * This check is only for data and will not apply for commands.
+ */
+static void zynq_qspi_write_tx_fifo(struct zynq_qspi *xqspi, unsigned int size)
+{
+ static const unsigned int offset[4] = {
+ ZYNQ_QSPI_TXD_00_01_OFFSET, ZYNQ_QSPI_TXD_00_10_OFFSET,
+ ZYNQ_QSPI_TXD_00_11_OFFSET, ZYNQ_QSPI_TXD_00_00_OFFSET };
+ unsigned int xsize;
+ u32 data;
+
+ if (xqspi->txbuf) {
+ data = 0xffffffff;
+ memcpy(&data, xqspi->txbuf, size);
+ xqspi->txbuf += size;
+ } else {
+ data = 0;
+ }
+
+ xqspi->bytes_to_transfer -= size;
+
+ xsize = size;
+ if (xqspi->is_dual && !xqspi->is_instr && (size % 2))
+ xsize++;
+ zynq_qspi_write(xqspi, offset[xsize - 1], data);
+}
+
+/**
+ * zynq_prepare_transfer_hardware - Prepares hardware for transfer.
+ * @master: Pointer to the spi_master structure which provides
+ * information about the controller.
+ *
+ * This function enables SPI master controller.
+ *
+ * Return: Always 0
+ */
+static int zynq_prepare_transfer_hardware(struct spi_master *master)
+{
+ struct zynq_qspi *xqspi = spi_master_get_devdata(master);
+
+ clk_enable(xqspi->refclk);
+ clk_enable(xqspi->pclk);
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET,
+ ZYNQ_QSPI_ENABLE_ENABLE_MASK);
+
+ return 0;
+}
+
+/**
+ * zynq_unprepare_transfer_hardware - Relaxes hardware after transfer
+ * @master: Pointer to the spi_master structure which provides
+ * information about the controller.
+ *
+ * This function disables the SPI master controller.
+ *
+ * Return: Always 0
+ */
+static int zynq_unprepare_transfer_hardware(struct spi_master *master)
+{
+ struct zynq_qspi *xqspi = spi_master_get_devdata(master);
+
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET, 0);
+ clk_disable(xqspi->refclk);
+ clk_disable(xqspi->pclk);
+
+ return 0;
+}
+
+/**
+ * zynq_qspi_chipselect - Select or deselect the chip select line
+ * @qspi: Pointer to the spi_device structure
+ * @is_high: Select(0) or deselect (1) the chip select line
+ */
+static void zynq_qspi_chipselect(struct spi_device *qspi, bool is_high)
+{
+ struct zynq_qspi *xqspi = spi_master_get_devdata(qspi->master);
+ u32 config_reg;
+#ifdef CONFIG_SPI_ZYNQ_QSPI_DUAL_STACKED
+ u32 lqspi_cfg_reg;
+#endif
+
+ config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_CONFIG_OFFSET);
+
+ /* Select upper/lower page before asserting CS */
+#ifdef CONFIG_SPI_ZYNQ_QSPI_DUAL_STACKED
+ lqspi_cfg_reg = zynq_qspi_read(xqspi,
+ ZYNQ_QSPI_LINEAR_CFG_OFFSET);
+ if (qspi->master->flags & SPI_MASTER_U_PAGE)
+ lqspi_cfg_reg |= ZYNQ_QSPI_LCFG_U_PAGE_MASK;
+ else
+ lqspi_cfg_reg &= ~ZYNQ_QSPI_LCFG_U_PAGE_MASK;
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_LINEAR_CFG_OFFSET,
+ lqspi_cfg_reg);
+#endif
+
+ if (is_high) {
+ /* Deselect the slave */
+ config_reg |= ZYNQ_QSPI_CONFIG_SSCTRL_MASK;
+ } else {
+ /* Select the slave */
+ config_reg &= ~ZYNQ_QSPI_CONFIG_SSCTRL_MASK;
+ config_reg |= (((~(BIT(qspi->chip_select))) <<
+ ZYNQ_QSPI_SS_SHIFT) &
+ ZYNQ_QSPI_CONFIG_SSCTRL_MASK);
+ xqspi->is_instr = 1;
+ }
+
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_CONFIG_OFFSET, config_reg);
+}
+
+/**
+ * zynq_qspi_setup_transfer - Configure QSPI controller for specified transfer
+ * @qspi: 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 QSPI controller for the next QSPI transfer and
+ * sets the requested clock frequency.
+ *
+ * Return: 0 on success and -EINVAL on invalid input parameter
+ *
+ * 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 QSPI
+ * controller the driver will set the highest or lowest frequency supported by
+ * controller.
+ */
+static int zynq_qspi_setup_transfer(struct spi_device *qspi,
+ struct spi_transfer *transfer)
+{
+ struct zynq_qspi *xqspi = spi_master_get_devdata(qspi->master);
+ u32 config_reg, req_hz, baud_rate_val = 0;
+
+ if (transfer)
+ req_hz = transfer->speed_hz;
+ else
+ req_hz = qspi->max_speed_hz;
+
+ /* Set the clock frequency */
+ /* If req_hz == 0, default to lowest speed */
+ while ((baud_rate_val < ZYNQ_QSPI_BAUD_DIV_MAX) &&
+ (clk_get_rate(xqspi->refclk) / (2 << baud_rate_val)) > req_hz)
+ baud_rate_val++;
+
+ config_reg = zynq_qspi_read(xqspi, ZYNQ_QSPI_CONFIG_OFFSET);
+
+ /* Set the QSPI clock phase and clock polarity */
+ config_reg &= (~ZYNQ_QSPI_CONFIG_CPHA_MASK) &
+ (~ZYNQ_QSPI_CONFIG_CPOL_MASK);
+ if (qspi->mode & SPI_CPHA)
+ config_reg |= ZYNQ_QSPI_CONFIG_CPHA_MASK;
+ if (qspi->mode & SPI_CPOL)
+ config_reg |= ZYNQ_QSPI_CONFIG_CPOL_MASK;
+
+ config_reg &= ~ZYNQ_QSPI_CONFIG_BDRATE_MASK;
+ config_reg |= (baud_rate_val << ZYNQ_QSPI_BAUD_DIV_SHIFT);
+
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_CONFIG_OFFSET, config_reg);
+
+ return 0;
+}
+
+/**
+ * zynq_qspi_setup - Configure the QSPI controller
+ * @qspi: Pointer to the spi_device structure
+ *
+ * Sets the operational mode of QSPI controller for the next QSPI transfer, baud
+ * rate and divisor value to setup the requested qspi clock.
+ *
+ * Return: 0 on success and error value on failure
+ */
+static int zynq_qspi_setup(struct spi_device *qspi)
+{
+ if (qspi->master->busy)
+ return -EBUSY;
+
+ return zynq_qspi_setup_transfer(qspi, NULL);
+}
+
+/**
+ * zynq_qspi_fill_tx_fifo - Fills the TX FIFO with as many bytes as possible
+ * @xqspi: Pointer to the zynq_qspi structure
+ * @txcount: Maximum number of words to write
+ * @txempty: Indicates that TxFIFO is empty
+ */
+static void zynq_qspi_fill_tx_fifo(struct zynq_qspi *xqspi, int txcount,
+ bool txempty)
+{
+ int count, len, k;
+
+ len = xqspi->bytes_to_transfer;
+ if (len && len < 4) {
+ /*
+ * We must empty the TxFIFO between accesses to TXD0,
+ * TXD1, TXD2, TXD3.
+ */
+ if (txempty)
+ zynq_qspi_write_tx_fifo(xqspi, len);
+ return;
+ }
+
+ count = len / 4;
+ if (count > txcount)
+ count = txcount;
+
+ if (xqspi->txbuf) {
+ writesl(xqspi->regs + ZYNQ_QSPI_TXD_00_00_OFFSET,
+ xqspi->txbuf, count);
+ xqspi->txbuf += count * 4;
+ } else {
+ for (k = 0; k < count; k++)
+ writel_relaxed(0, xqspi->regs +
+ ZYNQ_QSPI_TXD_00_00_OFFSET);
+ }
+ xqspi->bytes_to_transfer -= count * 4;
+}
+
+/**
+ * zynq_qspi_drain_rx_fifo - Drains the RX FIFO by as many bytes as possible
+ * @xqspi: Pointer to the zynq_qspi structure
+ * @rxcount: Maximum number of words to read
+ */
+static void zynq_qspi_drain_rx_fifo(struct zynq_qspi *xqspi, int rxcount)
+{
+ int count, len, k;
+
+ len = xqspi->bytes_to_receive - xqspi->bytes_to_transfer;
+ count = len / 4;
+ if (count > rxcount)
+ count = rxcount;
+
+ if (xqspi->rxbuf) {
+ readsl(xqspi->regs + ZYNQ_QSPI_RXD_OFFSET,
+ xqspi->rxbuf, count);
+ xqspi->rxbuf += count * 4;
+ } else {
+ for (k = 0; k < count; k++)
+ readl_relaxed(xqspi->regs + ZYNQ_QSPI_RXD_OFFSET);
+ }
+ xqspi->bytes_to_receive -= count * 4;
+ len -= count * 4;
+
+ if (len && len < 4 && count < rxcount)
+ zynq_qspi_read_rx_fifo(xqspi, len);
+}
+
+/**
+ * zynq_qspi_irq - Interrupt service routine of the QSPI controller
+ * @irq: IRQ number
+ * @dev_id: Pointer to the xqspi structure
+ *
+ * This function handles TX empty only.
+ * On TX empty interrupt this function reads the received data from RX FIFO and
+ * fills the TX FIFO if there is any data remaining to be transferred.
+ *
+ * Return: IRQ_HANDLED when interrupt is handled; IRQ_NONE otherwise.
+ */
+static irqreturn_t zynq_qspi_irq(int irq, void *dev_id)
+{
+ struct spi_master *master = dev_id;
+ struct zynq_qspi *xqspi = spi_master_get_devdata(master);
+ u32 intr_status;
+ bool txempty;
+
+ intr_status = zynq_qspi_read(xqspi, ZYNQ_QSPI_STATUS_OFFSET);
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_STATUS_OFFSET, intr_status);
+
+ if ((intr_status & ZYNQ_QSPI_IXR_TXNFULL_MASK) ||
+ (intr_status & ZYNQ_QSPI_IXR_RXNEMTY_MASK)) {
+ /*
+ * This bit is set when Tx FIFO has < THRESHOLD entries.
+ * We have the THRESHOLD value set to 1,
+ * so this bit indicates Tx FIFO is empty.
+ */
+ txempty = !!(intr_status & ZYNQ_QSPI_IXR_TXNFULL_MASK);
+
+ /* Read out the data from the RX FIFO */
+ zynq_qspi_drain_rx_fifo(xqspi, ZYNQ_QSPI_RX_THRESHOLD);
+
+ if (xqspi->bytes_to_transfer) {
+ /* There is more data to send */
+ zynq_qspi_fill_tx_fifo(xqspi, ZYNQ_QSPI_RX_THRESHOLD,
+ txempty);
+ } else {
+ /*
+ * If transfer and receive is completed then only send
+ * complete signal.
+ */
+ if (!xqspi->bytes_to_receive) {
+ zynq_qspi_write(xqspi,
+ ZYNQ_QSPI_IDIS_OFFSET,
+ ZYNQ_QSPI_IXR_ALL_MASK);
+ spi_finalize_current_transfer(master);
+ xqspi->is_instr = 0;
+ }
+ }
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+/**
+ * zynq_qspi_start_transfer - Initiates the QSPI transfer
+ * @master: Pointer to the spi_master structure which provides
+ * information about the controller.
+ * @qspi: Pointer to the spi_device structure
+ * @transfer: Pointer to the spi_transfer structure which provide information
+ * about next transfer parameters
+ *
+ * This function fills the TX FIFO, starts the QSPI transfer, and waits for the
+ * transfer to be completed.
+ *
+ * Return: Number of bytes transferred in the last transfer
+ */
+static int zynq_qspi_start_transfer(struct spi_master *master,
+ struct spi_device *qspi,
+ struct spi_transfer *transfer)
+{
+ struct zynq_qspi *xqspi = spi_master_get_devdata(master);
+
+ xqspi->txbuf = transfer->tx_buf;
+ xqspi->rxbuf = transfer->rx_buf;
+ xqspi->bytes_to_transfer = transfer->len;
+ xqspi->bytes_to_receive = transfer->len;
+
+ zynq_qspi_setup_transfer(qspi, transfer);
+
+ zynq_qspi_fill_tx_fifo(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
+
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
+ ZYNQ_QSPI_IXR_ALL_MASK);
+
+ return transfer->len;
+}
+
+/**
+ * zynq_qspi_probe - Probe method for the QSPI 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 failure
+ */
+static int zynq_qspi_probe(struct platform_device *pdev)
+{
+ int ret = 0;
+ struct spi_master *master;
+ struct zynq_qspi *xqspi;
+ struct resource *res;
+ u32 num_cs;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(*xqspi));
+ if (!master)
+ return -ENOMEM;
+
+ xqspi = spi_master_get_devdata(master);
+ master->dev.of_node = pdev->dev.of_node;
+ platform_set_drvdata(pdev, master);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ xqspi->regs = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(xqspi->regs)) {
+ ret = PTR_ERR(xqspi->regs);
+ goto remove_master;
+ }
+
+ if (of_property_read_u32(pdev->dev.of_node, "is-dual",
+ &xqspi->is_dual)) {
+ dev_warn(&pdev->dev, "couldn't determine configuration info");
+ dev_warn(&pdev->dev, "about dual memories. defaulting to single memory\n");
+ }
+
+ xqspi->pclk = devm_clk_get(&pdev->dev, "pclk");
+ if (IS_ERR(xqspi->pclk)) {
+ dev_err(&pdev->dev, "pclk clock not found.\n");
+ ret = PTR_ERR(xqspi->pclk);
+ goto remove_master;
+ }
+
+ xqspi->refclk = devm_clk_get(&pdev->dev, "ref_clk");
+ if (IS_ERR(xqspi->refclk)) {
+ dev_err(&pdev->dev, "ref_clk clock not found.\n");
+ ret = PTR_ERR(xqspi->refclk);
+ goto remove_master;
+ }
+
+ ret = clk_prepare_enable(xqspi->pclk);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to enable APB clock.\n");
+ goto remove_master;
+ }
+
+ ret = clk_prepare_enable(xqspi->refclk);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to enable device clock.\n");
+ goto clk_dis_pclk;
+ }
+
+ /* QSPI controller initializations */
+ zynq_qspi_init_hw(xqspi);
+
+ xqspi->irq = platform_get_irq(pdev, 0);
+ if (xqspi->irq <= 0) {
+ ret = -ENXIO;
+ dev_err(&pdev->dev, "irq resource not found\n");
+ goto remove_master;
+ }
+ ret = devm_request_irq(&pdev->dev, xqspi->irq, zynq_qspi_irq,
+ 0, pdev->name, master);
+ if (ret != 0) {
+ ret = -ENXIO;
+ dev_err(&pdev->dev, "request_irq failed\n");
+ goto remove_master;
+ }
+
+ ret = of_property_read_u32(pdev->dev.of_node, "num-cs",
+ &num_cs);
+ if (ret < 0)
+ master->num_chipselect = ZYNQ_QSPI_DEFAULT_NUM_CS;
+ else
+ master->num_chipselect = num_cs;
+
+ master->setup = zynq_qspi_setup;
+ master->set_cs = zynq_qspi_chipselect;
+ master->transfer_one = zynq_qspi_start_transfer;
+ master->prepare_transfer_hardware = zynq_prepare_transfer_hardware;
+ master->unprepare_transfer_hardware = zynq_unprepare_transfer_hardware;
+ master->flags = SPI_MASTER_QUAD_MODE;
+
+ master->max_speed_hz = clk_get_rate(xqspi->refclk) / 2;
+ master->bits_per_word_mask = SPI_BPW_MASK(8);
+ master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_RX_DUAL | SPI_RX_QUAD |
+ SPI_TX_DUAL | SPI_TX_QUAD;
+
+ ret = spi_register_master(master);
+ if (ret) {
+ dev_err(&pdev->dev, "spi_register_master failed\n");
+ goto clk_dis_all;
+ }
+
+ return ret;
+
+clk_dis_all:
+ clk_disable_unprepare(xqspi->refclk);
+clk_dis_pclk:
+ clk_disable_unprepare(xqspi->pclk);
+remove_master:
+ spi_master_put(master);
+ return ret;
+}
+
+/**
+ * zynq_qspi_remove - Remove method for the QSPI 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.
+ *
+ * Return: 0 on success and error value on failure
+ */
+static int zynq_qspi_remove(struct platform_device *pdev)
+{
+ struct spi_master *master = platform_get_drvdata(pdev);
+ struct zynq_qspi *xqspi = spi_master_get_devdata(master);
+
+ zynq_qspi_write(xqspi, ZYNQ_QSPI_ENABLE_OFFSET, 0);
+
+ clk_disable_unprepare(xqspi->refclk);
+ clk_disable_unprepare(xqspi->pclk);
+
+ spi_unregister_master(master);
+
+ return 0;
+}
+
+static const struct of_device_id zynq_qspi_of_match[] = {
+ { .compatible = "xlnx,zynq-qspi-1.0", },
+ { /* end of table */ }
+};
+MODULE_DEVICE_TABLE(of, zynq_qspi_of_match);
+
+/*
+ * zynq_qspi_driver - This structure defines the QSPI platform driver
+ */
+static struct platform_driver zynq_qspi_driver = {
+ .probe = zynq_qspi_probe,
+ .remove = zynq_qspi_remove,
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = zynq_qspi_of_match,
+ },
+};
+
+module_platform_driver(zynq_qspi_driver);
+
+MODULE_AUTHOR("Xilinx, Inc.");
+MODULE_DESCRIPTION("Xilinx Zynq QSPI driver");
+MODULE_LICENSE("GPL");
--
2.7.4