1 files changed, 431 insertions, 0 deletions
diff --git a/drivers/spi/spi-kspi2.c b/drivers/spi/spi-kspi2.c
new file mode 100644
index 000000000000..ca73ec52ce63
--- /dev/null
+++ b/drivers/spi/spi-kspi2.c
@@ -0,0 +1,431 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) KEBA Industrial Automation Gmbh 2024
+ *
+ * Driver for KEBA SPI host controller type 2 FPGA IP core
+ */
+
+#include <linux/iopoll.h>
+#include <linux/misc/keba.h>
+#include <linux/spi/spi.h>
+
+#define KSPI2 "kspi2"
+
+#define KSPI2_CLK_FREQ_REG	0x03
+#define  KSPI2_CLK_FREQ_MASK	0x0f
+#define  KSPI2_CLK_FREQ_62_5M	0x0
+#define  KSPI2_CLK_FREQ_33_3M	0x1
+#define  KSPI2_CLK_FREQ_125M	0x2
+#define  KSPI2_CLK_FREQ_50M	0x3
+#define  KSPI2_CLK_FREQ_100M	0x4
+
+#define KSPI2_CONTROL_REG		0x04
+#define  KSPI2_CONTROL_CLK_DIV_MAX	0x0f
+#define  KSPI2_CONTROL_CLK_DIV_MASK	0x0f
+#define  KSPI2_CONTROL_CPHA		0x10
+#define  KSPI2_CONTROL_CPOL		0x20
+#define  KSPI2_CONTROL_CLK_MODE_MASK	0x30
+#define  KSPI2_CONTROL_INIT		KSPI2_CONTROL_CLK_DIV_MAX
+
+#define KSPI2_STATUS_REG	0x08
+#define  KSPI2_STATUS_IN_USE	0x01
+#define  KSPI2_STATUS_BUSY	0x02
+
+#define KSPI2_DATA_REG	0x0c
+
+#define KSPI2_CS_NR_REG		0x10
+#define  KSPI2_CS_NR_NONE	0xff
+
+#define KSPI2_MODE_BITS	(SPI_CPHA | SPI_CPOL)
+#define KSPI2_NUM_CS	255
+
+#define KSPI2_SPEED_HZ_MIN(kspi)	(kspi->base_speed_hz / 65536)
+#define KSPI2_SPEED_HZ_MAX(kspi)	(kspi->base_speed_hz / 2)
+
+/* timeout is 10 times the time to transfer one byte at slowest clock */
+#define KSPI2_XFER_TIMEOUT_US(kspi)	(USEC_PER_SEC / \
+					 KSPI2_SPEED_HZ_MIN(kspi) * 8 * 10)
+
+#define KSPI2_INUSE_SLEEP_US	(2 * USEC_PER_MSEC)
+#define KSPI2_INUSE_TIMEOUT_US	(10 * USEC_PER_SEC)
+
+struct kspi2 {
+	struct keba_spi_auxdev *auxdev;
+	void __iomem *base;
+	struct spi_controller *host;
+
+	u32 base_speed_hz; /* SPI base clock frequency in HZ */
+	u8 control_shadow;
+
+	struct spi_device **device;
+	int device_size;
+};
+
+static int kspi2_inuse_lock(struct kspi2 *kspi)
+{
+	u8 sts;
+	int ret;
+
+	/*
+	 * The SPI controller has an IN_USE bit for locking access to the
+	 * controller. This enables the use of the SPI controller by other none
+	 * Linux processors.
+	 *
+	 * If the SPI controller is free, then the first read returns
+	 * IN_USE == 0. After that the SPI controller is locked and further
+	 * reads of IN_USE return 1.
+	 *
+	 * The SPI controller is unlocked by writing 1 into IN_USE.
+	 *
+	 * The IN_USE bit acts as a hardware semaphore for the SPI controller.
+	 * Poll for semaphore, but sleep while polling to free the CPU.
+	 */
+	ret = readb_poll_timeout(kspi->base + KSPI2_STATUS_REG,
+				 sts, (sts & KSPI2_STATUS_IN_USE) == 0,
+				 KSPI2_INUSE_SLEEP_US, KSPI2_INUSE_TIMEOUT_US);
+	if (ret != 0)
+		dev_warn(&kspi->auxdev->auxdev.dev, "%s err!\n", __func__);
+
+	return ret;
+}
+
+static void kspi2_inuse_unlock(struct kspi2 *kspi)
+{
+	/* unlock the controller by writing 1 into IN_USE */
+	iowrite8(KSPI2_STATUS_IN_USE, kspi->base + KSPI2_STATUS_REG);
+}
+
+static int kspi2_prepare_hardware(struct spi_controller *host)
+{
+	struct kspi2 *kspi = spi_controller_get_devdata(host);
+
+	/* lock hardware semaphore before actual use of controller */
+	return kspi2_inuse_lock(kspi);
+}
+
+static int kspi2_unprepare_hardware(struct spi_controller *host)
+{
+	struct kspi2 *kspi = spi_controller_get_devdata(host);
+
+	/* unlock hardware semaphore after actual use of controller */
+	kspi2_inuse_unlock(kspi);
+
+	return 0;
+}
+
+static u8 kspi2_calc_minimal_divider(struct kspi2 *kspi, u32 max_speed_hz)
+{
+	u8 div;
+
+	/*
+	 * Divider values 2, 4, 8, 16, ..., 65536 are possible. They are coded
+	 * as 0, 1, 2, 3, ..., 15 in the CONTROL_CLK_DIV bit.
+	 */
+	for (div = 0; div < KSPI2_CONTROL_CLK_DIV_MAX; div++) {
+		if ((kspi->base_speed_hz >> (div + 1)) <= max_speed_hz)
+			return div;
+	}
+
+	/* return divider for slowest clock if loop fails to find one */
+	return KSPI2_CONTROL_CLK_DIV_MAX;
+}
+
+static void kspi2_write_control_reg(struct kspi2 *kspi, u8 val, u8 mask)
+{
+	/* write control register only when necessary to improve performance */
+	if (val != (kspi->control_shadow & mask)) {
+		kspi->control_shadow = (kspi->control_shadow & ~mask) | val;
+		iowrite8(kspi->control_shadow, kspi->base + KSPI2_CONTROL_REG);
+	}
+}
+
+static int kspi2_txrx_byte(struct kspi2 *kspi, u8 tx, u8 *rx)
+{
+	u8 sts;
+	int ret;
+
+	/* start transfer by writing TX byte */
+	iowrite8(tx, kspi->base + KSPI2_DATA_REG);
+
+	/* wait till finished (BUSY == 0) */
+	ret = readb_poll_timeout(kspi->base + KSPI2_STATUS_REG,
+				 sts, (sts & KSPI2_STATUS_BUSY) == 0,
+				 0, KSPI2_XFER_TIMEOUT_US(kspi));
+	if (ret != 0)
+		return ret;
+
+	/* read RX byte */
+	if (rx)
+		*rx = ioread8(kspi->base + KSPI2_DATA_REG);
+
+	return 0;
+}
+
+static int kspi2_process_transfer(struct kspi2 *kspi, struct spi_transfer *t)
+{
+	u8 tx = 0;
+	u8 rx;
+	int i;
+	int ret;
+
+	for (i = 0; i < t->len; i++) {
+		if (t->tx_buf)
+			tx = ((const u8 *)t->tx_buf)[i];
+
+		ret = kspi2_txrx_byte(kspi, tx, &rx);
+		if (ret)
+			return ret;
+
+		if (t->rx_buf)
+			((u8 *)t->rx_buf)[i] = rx;
+	}
+
+	return 0;
+}
+
+static int kspi2_setup_transfer(struct kspi2 *kspi,
+				 struct spi_device *spi,
+				 struct spi_transfer *t)
+{
+	u32 max_speed_hz = spi->max_speed_hz;
+	u8 clk_div;
+
+	/*
+	 * spi_device (spi) has default parameters. Some of these can be
+	 * overwritten by parameters in spi_transfer (t).
+	 */
+	if (t->bits_per_word && ((t->bits_per_word % 8) != 0)) {
+		dev_err(&spi->dev, "Word width %d not supported!\n",
+			t->bits_per_word);
+
+		return -EINVAL;
+	}
+
+	if (t->speed_hz && (t->speed_hz < max_speed_hz))
+		max_speed_hz = t->speed_hz;
+
+	clk_div = kspi2_calc_minimal_divider(kspi, max_speed_hz);
+	kspi2_write_control_reg(kspi, clk_div, KSPI2_CONTROL_CLK_DIV_MASK);
+
+	return 0;
+}
+
+static int kspi2_transfer_one(struct spi_controller *host,
+			      struct spi_device *spi,
+			      struct spi_transfer *t)
+{
+	struct kspi2 *kspi = spi_controller_get_devdata(host);
+	int ret;
+
+	ret = kspi2_setup_transfer(kspi, spi, t);
+	if (ret != 0)
+		return ret;
+
+	if (t->len) {
+		ret = kspi2_process_transfer(kspi, t);
+		if (ret != 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+static void kspi2_set_cs(struct spi_device *spi, bool enable)
+{
+	struct spi_controller *host = spi->controller;
+	struct kspi2 *kspi = spi_controller_get_devdata(host);
+
+	/* controller is using active low chip select signals by design */
+	if (!enable)
+		iowrite8(spi_get_chipselect(spi, 0), kspi->base + KSPI2_CS_NR_REG);
+	else
+		iowrite8(KSPI2_CS_NR_NONE, kspi->base + KSPI2_CS_NR_REG);
+}
+
+static int kspi2_prepare_message(struct spi_controller *host,
+				 struct spi_message *msg)
+{
+	struct kspi2 *kspi = spi_controller_get_devdata(host);
+	struct spi_device *spi = msg->spi;
+	u8 mode = 0;
+
+	/* setup SPI clock phase and polarity */
+	if (spi->mode & SPI_CPHA)
+		mode |= KSPI2_CONTROL_CPHA;
+	if (spi->mode & SPI_CPOL)
+		mode |= KSPI2_CONTROL_CPOL;
+	kspi2_write_control_reg(kspi, mode, KSPI2_CONTROL_CLK_MODE_MASK);
+
+	return 0;
+}
+
+static int kspi2_setup(struct spi_device *spi)
+{
+	struct kspi2 *kspi = spi_controller_get_devdata(spi->controller);
+
+	/*
+	 * Check only parameters. Actual setup is done in kspi2_prepare_message
+	 * and directly before the SPI transfer starts.
+	 */
+
+	if (spi->mode & ~KSPI2_MODE_BITS) {
+		dev_err(&spi->dev, "Mode %d not supported!\n", spi->mode);
+
+		return -EINVAL;
+	}
+
+	if ((spi->bits_per_word % 8) != 0) {
+		dev_err(&spi->dev, "Word width %d not supported!\n",
+			spi->bits_per_word);
+
+		return -EINVAL;
+	}
+
+	if ((spi->max_speed_hz == 0) ||
+	    (spi->max_speed_hz > KSPI2_SPEED_HZ_MAX(kspi)))
+		spi->max_speed_hz = KSPI2_SPEED_HZ_MAX(kspi);
+
+	if (spi->max_speed_hz < KSPI2_SPEED_HZ_MIN(kspi)) {
+		dev_err(&spi->dev, "Requested speed of %d Hz is too low!\n",
+			spi->max_speed_hz);
+
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void kspi2_unregister_devices(struct kspi2 *kspi)
+{
+	int i;
+
+	for (i = 0; i < kspi->device_size; i++) {
+		struct spi_device *device = kspi->device[i];
+
+		if (device)
+			spi_unregister_device(device);
+	}
+}
+
+static int kspi2_register_devices(struct kspi2 *kspi)
+{
+	struct spi_board_info *info = kspi->auxdev->info;
+	int i;
+
+	/* register all known SPI devices */
+	for (i = 0; i < kspi->auxdev->info_size; i++) {
+		struct spi_device *device = spi_new_device(kspi->host, &info[i]);
+
+		if (!device) {
+			kspi2_unregister_devices(kspi);
+
+			return -ENODEV;
+		}
+		kspi->device[i] = device;
+	}
+
+	return 0;
+}
+
+static void kspi2_init(struct kspi2 *kspi)
+{
+	iowrite8(KSPI2_CONTROL_INIT, kspi->base + KSPI2_CONTROL_REG);
+	kspi->control_shadow = KSPI2_CONTROL_INIT;
+
+	iowrite8(KSPI2_CS_NR_NONE, kspi->base + KSPI2_CS_NR_REG);
+}
+
+static int kspi2_probe(struct auxiliary_device *auxdev,
+		       const struct auxiliary_device_id *id)
+{
+	struct device *dev = &auxdev->dev;
+	struct spi_controller *host;
+	struct kspi2 *kspi;
+	u8 clk_reg;
+	int ret;
+
+	host = devm_spi_alloc_host(dev, sizeof(struct kspi2));
+	if (!host)
+		return -ENOMEM;
+	kspi = spi_controller_get_devdata(host);
+	kspi->auxdev = container_of(auxdev, struct keba_spi_auxdev, auxdev);
+	kspi->host = host;
+	kspi->device = devm_kcalloc(dev, kspi->auxdev->info_size,
+				    sizeof(*kspi->device), GFP_KERNEL);
+	if (!kspi->device)
+		return -ENOMEM;
+	kspi->device_size = kspi->auxdev->info_size;
+	auxiliary_set_drvdata(auxdev, kspi);
+
+	kspi->base = devm_ioremap_resource(dev, &kspi->auxdev->io);
+	if (IS_ERR(kspi->base))
+		return PTR_ERR(kspi->base);
+
+	/* read the SPI base clock frequency */
+	clk_reg = ioread8(kspi->base + KSPI2_CLK_FREQ_REG);
+	switch (clk_reg & KSPI2_CLK_FREQ_MASK) {
+	case KSPI2_CLK_FREQ_62_5M:
+		kspi->base_speed_hz = 62500000; break;
+	case KSPI2_CLK_FREQ_33_3M:
+		kspi->base_speed_hz = 33333333; break;
+	case KSPI2_CLK_FREQ_125M:
+		kspi->base_speed_hz = 125000000; break;
+	case KSPI2_CLK_FREQ_50M:
+		kspi->base_speed_hz = 50000000; break;
+	case KSPI2_CLK_FREQ_100M:
+		kspi->base_speed_hz = 100000000; break;
+	default:
+		dev_err(dev, "Undefined SPI base clock frequency!\n");
+		return -ENODEV;
+	}
+
+	kspi2_init(kspi);
+
+	host->bus_num = -1;
+	host->num_chipselect = KSPI2_NUM_CS;
+	host->mode_bits = KSPI2_MODE_BITS;
+	host->setup = kspi2_setup;
+	host->prepare_transfer_hardware = kspi2_prepare_hardware;
+	host->unprepare_transfer_hardware = kspi2_unprepare_hardware;
+	host->prepare_message = kspi2_prepare_message;
+	host->set_cs = kspi2_set_cs;
+	host->transfer_one = kspi2_transfer_one;
+	ret = devm_spi_register_controller(dev, host);
+	if (ret) {
+		dev_err(dev, "Failed to register host (%d)!\n", ret);
+		return ret;
+	}
+
+	ret = kspi2_register_devices(kspi);
+	if (ret) {
+		dev_err(dev, "Failed to register devices (%d)!\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void kspi2_remove(struct auxiliary_device *auxdev)
+{
+	struct kspi2 *kspi = auxiliary_get_drvdata(auxdev);
+
+	kspi2_unregister_devices(kspi);
+}
+
+static const struct auxiliary_device_id kspi2_devtype_aux[] = {
+	{ .name = "keba.spi" },
+	{ },
+};
+MODULE_DEVICE_TABLE(auxiliary, kspi2_devtype_aux);
+
+static struct auxiliary_driver kspi2_driver_aux = {
+	.name = KSPI2,
+	.id_table = kspi2_devtype_aux,
+	.probe = kspi2_probe,
+	.remove = kspi2_remove,
+};
+module_auxiliary_driver(kspi2_driver_aux);
+
+MODULE_AUTHOR("Gerhard Engleder <eg@keba.com>");
+MODULE_DESCRIPTION("KEBA SPI host controller driver");
+MODULE_LICENSE("GPL");