--- /dev/null
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+//
+// AMD SPI controller driver
+//
+// Copyright (c) 2020, Advanced Micro Devices, Inc.
+//
+// Author: Sanjay R Mehta <sanju.mehta@amd.com>
+
+#include <linux/acpi.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/spi/spi.h>
+
+#define AMD_SPI_CTRL0_REG 0x00
+#define AMD_SPI_EXEC_CMD BIT(16)
+#define AMD_SPI_FIFO_CLEAR BIT(20)
+#define AMD_SPI_BUSY BIT(31)
+
+#define AMD_SPI_OPCODE_MASK 0xFF
+
+#define AMD_SPI_ALT_CS_REG 0x1D
+#define AMD_SPI_ALT_CS_MASK 0x3
+
+#define AMD_SPI_FIFO_BASE 0x80
+#define AMD_SPI_TX_COUNT_REG 0x48
+#define AMD_SPI_RX_COUNT_REG 0x4B
+#define AMD_SPI_STATUS_REG 0x4C
+
+#define AMD_SPI_MEM_SIZE 200
+
+/* M_CMD OP codes for SPI */
+#define AMD_SPI_XFER_TX 1
+#define AMD_SPI_XFER_RX 2
+
+struct amd_spi {
+ void __iomem *io_remap_addr;
+ unsigned long io_base_addr;
+ u32 rom_addr;
+ struct spi_master *master;
+ u8 chip_select;
+};
+
+static inline u8 amd_spi_readreg8(struct spi_master *master, int idx)
+{
+ struct amd_spi *amd_spi = spi_master_get_devdata(master);
+
+ return ioread8((u8 __iomem *)amd_spi->io_remap_addr + idx);
+}
+
+static inline void amd_spi_writereg8(struct spi_master *master, int idx,
+ u8 val)
+{
+ struct amd_spi *amd_spi = spi_master_get_devdata(master);
+
+ iowrite8(val, ((u8 __iomem *)amd_spi->io_remap_addr + idx));
+}
+
+static inline void amd_spi_setclear_reg8(struct spi_master *master, int idx,
+ u8 set, u8 clear)
+{
+ u8 tmp = amd_spi_readreg8(master, idx);
+
+ tmp = (tmp & ~clear) | set;
+ amd_spi_writereg8(master, idx, tmp);
+}
+
+static inline u32 amd_spi_readreg32(struct spi_master *master, int idx)
+{
+ struct amd_spi *amd_spi = spi_master_get_devdata(master);
+
+ return ioread32((u8 __iomem *)amd_spi->io_remap_addr + idx);
+}
+
+static inline void amd_spi_writereg32(struct spi_master *master, int idx,
+ u32 val)
+{
+ struct amd_spi *amd_spi = spi_master_get_devdata(master);
+
+ iowrite32(val, ((u8 __iomem *)amd_spi->io_remap_addr + idx));
+}
+
+static inline void amd_spi_setclear_reg32(struct spi_master *master, int idx,
+ u32 set, u32 clear)
+{
+ u32 tmp = amd_spi_readreg32(master, idx);
+
+ tmp = (tmp & ~clear) | set;
+ amd_spi_writereg32(master, idx, tmp);
+}
+
+static void amd_spi_select_chip(struct spi_master *master)
+{
+ struct amd_spi *amd_spi = spi_master_get_devdata(master);
+ u8 chip_select = amd_spi->chip_select;
+
+ amd_spi_setclear_reg8(master, AMD_SPI_ALT_CS_REG, chip_select,
+ AMD_SPI_ALT_CS_MASK);
+}
+
+static void amd_spi_clear_fifo_ptr(struct spi_master *master)
+{
+ amd_spi_setclear_reg32(master, AMD_SPI_CTRL0_REG, AMD_SPI_FIFO_CLEAR,
+ AMD_SPI_FIFO_CLEAR);
+}
+
+static void amd_spi_set_opcode(struct spi_master *master, u8 cmd_opcode)
+{
+ amd_spi_setclear_reg32(master, AMD_SPI_CTRL0_REG, cmd_opcode,
+ AMD_SPI_OPCODE_MASK);
+}
+
+static inline void amd_spi_set_rx_count(struct spi_master *master,
+ u8 rx_count)
+{
+ amd_spi_setclear_reg8(master, AMD_SPI_RX_COUNT_REG, rx_count, 0xff);
+}
+
+static inline void amd_spi_set_tx_count(struct spi_master *master,
+ u8 tx_count)
+{
+ amd_spi_setclear_reg8(master, AMD_SPI_TX_COUNT_REG, tx_count, 0xff);
+}
+
+static inline int amd_spi_busy_wait(struct amd_spi *amd_spi)
+{
+ bool spi_busy;
+ int timeout = 100000;
+
+ /* poll for SPI bus to become idle */
+ spi_busy = (ioread32((u8 __iomem *)amd_spi->io_remap_addr +
+ AMD_SPI_CTRL0_REG) & AMD_SPI_BUSY) == AMD_SPI_BUSY;
+ while (spi_busy) {
+ usleep_range(10, 20);
+ if (timeout-- < 0)
+ return -ETIMEDOUT;
+
+ spi_busy = (ioread32((u8 __iomem *)amd_spi->io_remap_addr +
+ AMD_SPI_CTRL0_REG) & AMD_SPI_BUSY) == AMD_SPI_BUSY;
+ }
+
+ return 0;
+}
+
+static void amd_spi_execute_opcode(struct spi_master *master)
+{
+ struct amd_spi *amd_spi = spi_master_get_devdata(master);
+
+ /* Set ExecuteOpCode bit in the CTRL0 register */
+ amd_spi_setclear_reg32(master, AMD_SPI_CTRL0_REG, AMD_SPI_EXEC_CMD,
+ AMD_SPI_EXEC_CMD);
+
+ amd_spi_busy_wait(amd_spi);
+}
+
+static int amd_spi_master_setup(struct spi_device *spi)
+{
+ struct spi_master *master = spi->master;
+
+ amd_spi_clear_fifo_ptr(master);
+
+ return 0;
+}
+
+static inline int amd_spi_fifo_xfer(struct amd_spi *amd_spi,
+ struct spi_message *message)
+{
+ struct spi_master *master = amd_spi->master;
+ struct spi_transfer *xfer = NULL;
+ u8 cmd_opcode, opcode = 0;
+ u8 *buf = NULL;
+ u32 m_cmd = 0;
+ u32 i = 0;
+ u32 tx_len = 0, rx_len = 0;
+
+ list_for_each_entry(xfer, &message->transfers,
+ transfer_list) {
+ if (xfer->rx_buf)
+ m_cmd = AMD_SPI_XFER_RX;
+ if (xfer->tx_buf)
+ m_cmd = AMD_SPI_XFER_TX;
+
+ if (m_cmd & AMD_SPI_XFER_TX) {
+ buf = (u8 *)xfer->tx_buf;
+ tx_len = xfer->len - 1;
+ cmd_opcode = *(u8 *)xfer->tx_buf;
+ buf++;
+ amd_spi_set_opcode(master, cmd_opcode);
+
+ /* Write data into the FIFO. */
+ for (i = 0; i < tx_len; i++) {
+ iowrite8(buf[i],
+ ((u8 __iomem *)amd_spi->io_remap_addr +
+ AMD_SPI_FIFO_BASE + i));
+ }
+
+ amd_spi_set_tx_count(master, tx_len);
+ amd_spi_clear_fifo_ptr(master);
+ /* Execute command */
+ amd_spi_execute_opcode(master);
+ }
+ if (m_cmd & AMD_SPI_XFER_RX) {
+ /*
+ * Store no. of bytes to be received from
+ * FIFO
+ */
+ rx_len = xfer->len;
+ buf = (u8 *)xfer->rx_buf;
+ amd_spi_set_rx_count(master, rx_len);
+ amd_spi_clear_fifo_ptr(master);
+ /* Execute command */
+ amd_spi_execute_opcode(master);
+ /* Read data from FIFO to receive buffer */
+ for (i = 0; i < rx_len; i++)
+ buf[i] = amd_spi_readreg8(master,
+ AMD_SPI_FIFO_BASE +
+ tx_len + i);
+ }
+ }
+
+ /* Update statistics */
+ message->actual_length = tx_len + rx_len + 1;
+ /* complete the transaction */
+ message->status = 0;
+ spi_finalize_current_message(master);
+
+ return 0;
+}
+
+static int amd_spi_master_transfer(struct spi_master *master,
+ struct spi_message *msg)
+{
+ struct amd_spi *amd_spi = spi_master_get_devdata(master);
+ struct spi_device *spi = msg->spi;
+
+ amd_spi->chip_select = spi->chip_select;
+ amd_spi_select_chip(master);
+
+ /*
+ * Extract spi_transfers from the spi message and
+ * program the controller.
+ */
+ amd_spi_fifo_xfer(amd_spi, msg);
+
+ return 0;
+}
+
+static int amd_spi_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct spi_master *master;
+ struct amd_spi *amd_spi;
+ struct resource *res;
+ int err = 0;
+
+ /* Allocate storage for spi_master and driver private data */
+ master = spi_alloc_master(dev, sizeof(struct amd_spi));
+ if (!master) {
+ dev_err(dev, "Error allocating SPI master\n");
+ return -ENOMEM;
+ }
+
+ amd_spi = spi_master_get_devdata(master);
+ amd_spi->master = master;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ amd_spi->io_remap_addr = devm_ioremap_resource(&pdev->dev, res);
+
+ if (!amd_spi->io_remap_addr) {
+ dev_err(dev, "error %d ioremap of SPI registers failed\n", err);
+ err = -ENOMEM;
+ goto err_free_master;
+ }
+ dev_dbg(dev, "io_remap_address: %p\n", amd_spi->io_remap_addr);
+
+ /* Initialize the spi_master fields */
+ master->bus_num = 0;
+ master->num_chipselect = 4;
+ master->mode_bits = 0;
+ master->flags = SPI_MASTER_HALF_DUPLEX;
+ master->setup = amd_spi_master_setup;
+ master->transfer_one_message = amd_spi_master_transfer;
+
+ /* Register the controller with SPI framework */
+ err = spi_register_master(master);
+ if (err) {
+ dev_err(dev, "error %d registering SPI controller\n", err);
+ goto err_iounmap;
+ }
+ platform_set_drvdata(pdev, amd_spi);
+
+ return 0;
+
+err_iounmap:
+ iounmap(amd_spi->io_remap_addr);
+err_free_master:
+ spi_master_put(master);
+
+ return 0;
+}
+
+static int amd_spi_remove(struct platform_device *pdev)
+{
+ struct amd_spi *amd_spi = platform_get_drvdata(pdev);
+
+ spi_unregister_master(amd_spi->master);
+ spi_master_put(amd_spi->master);
+ platform_set_drvdata(pdev, NULL);
+
+ return 0;
+}
+
+static const struct acpi_device_id spi_acpi_match[] = {
+ { "AMDI0061", 0 },
+ {},
+};
+MODULE_DEVICE_TABLE(acpi, spi_acpi_match);
+
+static struct platform_driver amd_spi_driver = {
+ .driver = {
+ .name = "amd_spi",
+ .acpi_match_table = ACPI_PTR(spi_acpi_match),
+ },
+ .probe = amd_spi_probe,
+ .remove = amd_spi_remove,
+};
+
+module_platform_driver(amd_spi_driver);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Sanjay Mehta <sanju.mehta@amd.com>");
+MODULE_DESCRIPTION("AMD SPI Master Controller Driver");
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