[PATCH v2 1/2] spi: Port SiFive SPI controller driver

[Ahmad Fatoum <ahmad@a3f.at>]

Import the U-Boot v2022.04-rc2 driver to enable access to SPI flash and
SD over SPI on the HiFive Unleashed. Tested with QEMU.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
---
v1 -> v2:
  - remove unused wait_for_bit (Sascha)
  - move prep and CS handling out of transfer_one into callers (Sascha)
  - Use nbytes instead of bitlen as code is bytewise anyway (Sascha)
  - remove superfluous pos variable (Sascha)
---
 drivers/spi/Kconfig      |   6 +
 drivers/spi/Makefile     |   1 +
 drivers/spi/spi-sifive.c | 521 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 528 insertions(+)
 create mode 100644 drivers/spi/spi-sifive.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 7df7561718c2..8935feb97b99 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -124,6 +124,12 @@ config SPI_NXP_FLEXSPI
 	  This controller does not support generic SPI messages and only
 	  supports the high-level SPI memory interface.
 
+config SPI_SIFIVE
+	tristate "SiFive SPI controller"
+	depends on SOC_SIFIVE || COMPILE_TEST
+	help
+	  This exposes the SPI controller IP from SiFive.
+
 endif
 
 endmenu
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 64c8e2645a94..3455eea86988 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -17,3 +17,4 @@ obj-$(CONFIG_DRIVER_SPI_DSPI) += dspi_spi.o
 obj-$(CONFIG_SPI_ZYNQ_QSPI) += zynq_qspi.o
 obj-$(CONFIG_SPI_NXP_FLEXSPI) += spi-nxp-fspi.o
 obj-$(CONFIG_DRIVER_SPI_STM32) += stm32_spi.o
+obj-$(CONFIG_SPI_SIFIVE) += spi-sifive.o
diff --git a/drivers/spi/spi-sifive.c b/drivers/spi/spi-sifive.c
new file mode 100644
index 000000000000..713bcc0c3bd8
--- /dev/null
+++ b/drivers/spi/spi-sifive.c
@@ -0,0 +1,521 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 SiFive, Inc.
+ * Copyright 2019 Bhargav Shah <bhargavshah1988@gmail.com>
+ *
+ * SiFive SPI controller driver (master mode only)
+ */
+
+#include <common.h>
+#include <linux/clk.h>
+#include <driver.h>
+#include <init.h>
+#include <errno.h>
+#include <linux/reset.h>
+#include <spi/spi.h>
+#include <linux/spi/spi-mem.h>
+#include <linux/bitops.h>
+#include <clock.h>
+#include <gpio.h>
+#include <of_gpio.h>
+#include <linux/bitfield.h>
+#include <linux/iopoll.h>
+#include <linux/log2.h>
+
+#define SIFIVE_SPI_MAX_CS		32
+
+#define SIFIVE_SPI_DEFAULT_DEPTH	8
+#define SIFIVE_SPI_DEFAULT_BITS		8
+
+/* register offsets */
+#define SIFIVE_SPI_REG_SCKDIV            0x00 /* Serial clock divisor */
+#define SIFIVE_SPI_REG_SCKMODE           0x04 /* Serial clock mode */
+#define SIFIVE_SPI_REG_CSID              0x10 /* Chip select ID */
+#define SIFIVE_SPI_REG_CSDEF             0x14 /* Chip select default */
+#define SIFIVE_SPI_REG_CSMODE            0x18 /* Chip select mode */
+#define SIFIVE_SPI_REG_DELAY0            0x28 /* Delay control 0 */
+#define SIFIVE_SPI_REG_DELAY1            0x2c /* Delay control 1 */
+#define SIFIVE_SPI_REG_FMT               0x40 /* Frame format */
+#define SIFIVE_SPI_REG_TXDATA            0x48 /* Tx FIFO data */
+#define SIFIVE_SPI_REG_RXDATA            0x4c /* Rx FIFO data */
+#define SIFIVE_SPI_REG_TXMARK            0x50 /* Tx FIFO watermark */
+#define SIFIVE_SPI_REG_RXMARK            0x54 /* Rx FIFO watermark */
+#define SIFIVE_SPI_REG_FCTRL             0x60 /* SPI flash interface control */
+#define SIFIVE_SPI_REG_FFMT              0x64 /* SPI flash instruction format */
+#define SIFIVE_SPI_REG_IE                0x70 /* Interrupt Enable Register */
+#define SIFIVE_SPI_REG_IP                0x74 /* Interrupt Pendings Register */
+
+/* sckdiv bits */
+#define SIFIVE_SPI_SCKDIV_DIV_MASK       0xfffU
+
+/* sckmode bits */
+#define SIFIVE_SPI_SCKMODE_PHA           BIT(0)
+#define SIFIVE_SPI_SCKMODE_POL           BIT(1)
+#define SIFIVE_SPI_SCKMODE_MODE_MASK     (SIFIVE_SPI_SCKMODE_PHA | \
+					  SIFIVE_SPI_SCKMODE_POL)
+
+/* csmode bits */
+#define SIFIVE_SPI_CSMODE_MODE_AUTO      0U
+#define SIFIVE_SPI_CSMODE_MODE_HOLD      2U
+#define SIFIVE_SPI_CSMODE_MODE_OFF       3U
+
+/* delay0 bits */
+#define SIFIVE_SPI_DELAY0_CSSCK(x)       ((u32)(x))
+#define SIFIVE_SPI_DELAY0_CSSCK_MASK     0xffU
+#define SIFIVE_SPI_DELAY0_SCKCS(x)       ((u32)(x) << 16)
+#define SIFIVE_SPI_DELAY0_SCKCS_MASK     (0xffU << 16)
+
+/* delay1 bits */
+#define SIFIVE_SPI_DELAY1_INTERCS(x)     ((u32)(x))
+#define SIFIVE_SPI_DELAY1_INTERCS_MASK   0xffU
+#define SIFIVE_SPI_DELAY1_INTERXFR(x)    ((u32)(x) << 16)
+#define SIFIVE_SPI_DELAY1_INTERXFR_MASK  (0xffU << 16)
+
+/* fmt bits */
+#define SIFIVE_SPI_FMT_PROTO_SINGLE      0U
+#define SIFIVE_SPI_FMT_PROTO_DUAL        1U
+#define SIFIVE_SPI_FMT_PROTO_QUAD        2U
+#define SIFIVE_SPI_FMT_PROTO_MASK        3U
+#define SIFIVE_SPI_FMT_ENDIAN            BIT(2)
+#define SIFIVE_SPI_FMT_DIR               BIT(3)
+#define SIFIVE_SPI_FMT_LEN(x)            ((u32)(x) << 16)
+#define SIFIVE_SPI_FMT_LEN_MASK          (0xfU << 16)
+
+/* txdata bits */
+#define SIFIVE_SPI_TXDATA_DATA_MASK      0xffU
+#define SIFIVE_SPI_TXDATA_FULL           BIT(31)
+
+/* rxdata bits */
+#define SIFIVE_SPI_RXDATA_DATA_MASK      0xffU
+#define SIFIVE_SPI_RXDATA_EMPTY          BIT(31)
+
+/* ie and ip bits */
+#define SIFIVE_SPI_IP_TXWM               BIT(0)
+#define SIFIVE_SPI_IP_RXWM               BIT(1)
+
+/* format protocol */
+#define SIFIVE_SPI_PROTO_QUAD		4 /* 4 lines I/O protocol transfer */
+#define SIFIVE_SPI_PROTO_DUAL		2 /* 2 lines I/O protocol transfer */
+#define SIFIVE_SPI_PROTO_SINGLE		1 /* 1 line I/O protocol transfer */
+
+#define SPI_XFER_BEGIN  0x01                    /* Assert CS before transfer */
+#define SPI_XFER_END    0x02                    /* Deassert CS after transfer */
+
+struct sifive_spi {
+	struct spi_controller ctlr;
+	void __iomem	*regs;		/* base address of the registers */
+	u32		fifo_depth;
+	u32		bits_per_word;
+	u32		cs_inactive;	/* Level of the CS pins when inactive*/
+	u32		freq;
+	u8		fmt_proto;
+};
+
+static inline struct sifive_spi *to_sifive_spi(struct spi_controller *ctlr)
+{
+	return container_of(ctlr, struct sifive_spi, ctlr);
+}
+
+static void sifive_spi_prep_device(struct sifive_spi *spi,
+				   struct spi_device *spi_dev)
+{
+	/* Update the chip select polarity */
+	if (spi_dev->mode & SPI_CS_HIGH)
+		spi->cs_inactive &= ~BIT(spi_dev->chip_select);
+	else
+		spi->cs_inactive |= BIT(spi_dev->chip_select);
+	writel(spi->cs_inactive, spi->regs + SIFIVE_SPI_REG_CSDEF);
+
+	/* Select the correct device */
+	writel(spi_dev->chip_select, spi->regs + SIFIVE_SPI_REG_CSID);
+}
+
+static void sifive_spi_set_cs(struct sifive_spi *spi,
+			     struct spi_device *spi_dev)
+{
+	u32 cs_mode = SIFIVE_SPI_CSMODE_MODE_HOLD;
+
+	if (spi_dev->mode & SPI_CS_HIGH)
+		cs_mode = SIFIVE_SPI_CSMODE_MODE_AUTO;
+
+	writel(cs_mode, spi->regs + SIFIVE_SPI_REG_CSMODE);
+}
+
+static void sifive_spi_clear_cs(struct sifive_spi *spi)
+{
+	writel(SIFIVE_SPI_CSMODE_MODE_AUTO, spi->regs + SIFIVE_SPI_REG_CSMODE);
+}
+
+static void sifive_spi_prep_transfer(struct sifive_spi *spi,
+				     struct spi_device *spi_dev,
+				     u8 *rx_ptr)
+{
+	u32 cr;
+
+	/* Modify the SPI protocol mode */
+	cr = readl(spi->regs + SIFIVE_SPI_REG_FMT);
+
+	/* Bits per word ? */
+	cr &= ~SIFIVE_SPI_FMT_LEN_MASK;
+	cr |= SIFIVE_SPI_FMT_LEN(spi->bits_per_word);
+
+	/* LSB first? */
+	cr &= ~SIFIVE_SPI_FMT_ENDIAN;
+	if (spi_dev->mode & SPI_LSB_FIRST)
+		cr |= SIFIVE_SPI_FMT_ENDIAN;
+
+	/* Number of wires ? */
+	cr &= ~SIFIVE_SPI_FMT_PROTO_MASK;
+	switch (spi->fmt_proto) {
+	case SIFIVE_SPI_PROTO_QUAD:
+		cr |= SIFIVE_SPI_FMT_PROTO_QUAD;
+		break;
+	case SIFIVE_SPI_PROTO_DUAL:
+		cr |= SIFIVE_SPI_FMT_PROTO_DUAL;
+		break;
+	default:
+		cr |= SIFIVE_SPI_FMT_PROTO_SINGLE;
+		break;
+	}
+
+	/* SPI direction in/out ? */
+	cr &= ~SIFIVE_SPI_FMT_DIR;
+	if (!rx_ptr)
+		cr |= SIFIVE_SPI_FMT_DIR;
+
+	writel(cr, spi->regs + SIFIVE_SPI_REG_FMT);
+}
+
+static void sifive_spi_rx(struct sifive_spi *spi, u8 *rx_ptr)
+{
+	u32 data;
+
+	do {
+		data = readl(spi->regs + SIFIVE_SPI_REG_RXDATA);
+	} while (data & SIFIVE_SPI_RXDATA_EMPTY);
+
+	if (rx_ptr)
+		*rx_ptr = data & SIFIVE_SPI_RXDATA_DATA_MASK;
+}
+
+static void sifive_spi_tx(struct sifive_spi *spi, const u8 *tx_ptr)
+{
+	u32 data;
+	u8 tx_data = (tx_ptr) ? *tx_ptr & SIFIVE_SPI_TXDATA_DATA_MASK :
+				SIFIVE_SPI_TXDATA_DATA_MASK;
+
+	do {
+		data = readl(spi->regs + SIFIVE_SPI_REG_TXDATA);
+	} while (data & SIFIVE_SPI_TXDATA_FULL);
+
+	writel(tx_data, spi->regs + SIFIVE_SPI_REG_TXDATA);
+}
+
+static int sifive_spi_wait(struct sifive_spi *spi, u32 mask)
+{
+	u32 val;
+
+	return readl_poll_timeout(spi->regs + SIFIVE_SPI_REG_IP, val,
+				  (val & mask) == mask, 100 * USEC_PER_MSEC);
+}
+
+static int sifive_spi_transfer_one(struct spi_device *spi_dev, unsigned int nbytes,
+				   const void *dout, void *din)
+{
+	struct sifive_spi *spi = to_sifive_spi(spi_dev->controller);
+	const u8 *tx_ptr = dout;
+	u8 *rx_ptr = din;
+	int ret;
+
+	sifive_spi_prep_transfer(spi, spi_dev, rx_ptr);
+
+	while (nbytes) {
+		unsigned int n_words = min(nbytes, spi->fifo_depth);
+		unsigned int tx_words, rx_words;
+
+		/* Enqueue n_words for transmission */
+		for (tx_words = 0; tx_words < n_words; tx_words++) {
+			if (!tx_ptr)
+				sifive_spi_tx(spi, NULL);
+			else
+				sifive_spi_tx(spi, tx_ptr++);
+		}
+
+		if (rx_ptr) {
+			/* Wait for transmission + reception to complete */
+			writel(n_words - 1, spi->regs + SIFIVE_SPI_REG_RXMARK);
+			ret = sifive_spi_wait(spi, SIFIVE_SPI_IP_RXWM);
+			if (ret)
+				return ret;
+
+			/* Read out all the data from the RX FIFO */
+			for (rx_words = 0; rx_words < n_words; rx_words++)
+				sifive_spi_rx(spi, rx_ptr++);
+		} else {
+			/* Wait for transmission to complete */
+			ret = sifive_spi_wait(spi, SIFIVE_SPI_IP_TXWM);
+			if (ret)
+				return ret;
+		}
+
+		nbytes -= n_words;
+	}
+
+	return 0;
+}
+
+static int sifive_spi_transfer(struct spi_device *spi_dev, struct spi_message *msg)
+{
+	struct spi_controller *ctlr = spi_dev->controller;
+	struct sifive_spi *spi = to_sifive_spi(ctlr);
+	struct spi_transfer *t;
+	int ret = 0;
+
+	if (list_empty(&msg->transfers))
+		return 0;
+
+	msg->actual_length = 0;
+
+	sifive_spi_prep_device(spi, spi_dev);
+	sifive_spi_set_cs(spi, spi_dev);
+
+	dev_dbg(ctlr->dev, "transfer start actual_length=%i\n", msg->actual_length);
+	list_for_each_entry(t, &msg->transfers, transfer_list) {
+		dev_dbg(ctlr->dev, "  xfer %p: len %u tx %p rx %p\n",
+			t, t->len, t->tx_buf, t->rx_buf);
+
+		ret = sifive_spi_transfer_one(spi_dev, t->len,
+					      t->tx_buf, t->rx_buf);
+		if (ret < 0)
+			goto out;
+		msg->actual_length += t->len;
+	}
+	dev_dbg(ctlr->dev, "transfer done actual_length=%i\n", msg->actual_length);
+
+out:
+	sifive_spi_clear_cs(spi);
+	return ret;
+}
+
+static int sifive_spi_exec_op(struct spi_mem *mem,
+			      const struct spi_mem_op *op)
+{
+	struct spi_device *spi_dev = mem->spi;
+	struct device_d *dev = &spi_dev->dev;
+	struct sifive_spi *spi = spi_controller_get_devdata(spi_dev->controller);
+	u8 opcode = op->cmd.opcode;
+	int ret;
+
+	spi->fmt_proto = op->cmd.buswidth;
+
+	sifive_spi_prep_device(spi, spi_dev);
+	sifive_spi_set_cs(spi, spi_dev);
+
+	/* send the opcode */
+	ret = sifive_spi_transfer_one(spi_dev, 1, &opcode, NULL);
+	if (ret < 0) {
+		dev_err(dev, "failed to xfer opcode\n");
+		goto out;
+	}
+
+	if (!op->addr.nbytes && !op->data.nbytes)
+		goto out;
+
+	/* send the addr + dummy */
+	if (op->addr.nbytes) {
+		int i, op_len = op->addr.nbytes + op->dummy.nbytes;
+		u8 *op_buf;
+
+		op_buf = malloc(op_len);
+		if (!op_buf) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		/* fill address */
+		for (i = 0; i < op->addr.nbytes; i++)
+			op_buf[i] = op->addr.val >>
+				(8 * (op->addr.nbytes - i - 1));
+
+		/* fill dummy */
+		memset(op_buf + op->addr.nbytes, 0xff, op->dummy.nbytes);
+
+		spi->fmt_proto = op->addr.buswidth;
+
+		ret = sifive_spi_transfer_one(spi_dev, op_len, op_buf, NULL);
+		free(op_buf);
+		if (ret < 0) {
+			dev_err(dev, "failed to xfer addr + dummy\n");
+			goto out;
+		}
+	}
+
+	/* send/received the data */
+	if (op->data.nbytes) {
+		const void *tx_buf = NULL;
+		void *rx_buf = NULL;
+
+		if (op->data.dir == SPI_MEM_DATA_IN)
+			rx_buf = op->data.buf.in;
+		else
+			tx_buf = op->data.buf.out;
+
+		spi->fmt_proto = op->data.buswidth;
+
+		ret = sifive_spi_transfer_one(spi_dev, op->data.nbytes,
+				      tx_buf, rx_buf);
+		if (ret) {
+			dev_err(dev, "failed to xfer data\n");
+			goto out;
+		}
+	}
+
+out:
+	sifive_spi_clear_cs(spi);
+	return ret;
+}
+
+static void sifive_spi_set_speed(struct sifive_spi *spi, uint speed)
+{
+	u32 scale;
+
+	if (speed > spi->freq)
+		speed = spi->freq;
+
+	/* Cofigure max speed */
+	scale = (DIV_ROUND_UP(spi->freq >> 1, speed) - 1)
+					& SIFIVE_SPI_SCKDIV_DIV_MASK;
+	writel(scale, spi->regs + SIFIVE_SPI_REG_SCKDIV);
+}
+
+static void sifive_spi_set_mode(struct sifive_spi *spi, uint mode)
+{
+	u32 cr;
+
+	/* Switch clock mode bits */
+	cr = readl(spi->regs + SIFIVE_SPI_REG_SCKMODE) &
+				~SIFIVE_SPI_SCKMODE_MODE_MASK;
+	if (mode & SPI_CPHA)
+		cr |= SIFIVE_SPI_SCKMODE_PHA;
+	if (mode & SPI_CPOL)
+		cr |= SIFIVE_SPI_SCKMODE_POL;
+
+	writel(cr, spi->regs + SIFIVE_SPI_REG_SCKMODE);
+}
+
+static int sifive_spi_setup(struct spi_device *spi_dev)
+{
+	struct sifive_spi *spi = to_sifive_spi(spi_dev->controller);
+
+	sifive_spi_set_mode(spi, spi_dev->mode);
+	sifive_spi_set_speed(spi, spi_dev->max_speed_hz);
+
+	return 0;
+}
+
+static void sifive_spi_init_hw(struct sifive_spi *spi)
+{
+	struct device_d *dev = spi->ctlr.dev;
+	u32 cs_bits;
+
+	/* probe the number of CS lines */
+	spi->cs_inactive = readl(spi->regs + SIFIVE_SPI_REG_CSDEF);
+	writel(0xffffffffU, spi->regs + SIFIVE_SPI_REG_CSDEF);
+	cs_bits = readl(spi->regs + SIFIVE_SPI_REG_CSDEF);
+	writel(spi->cs_inactive, spi->regs + SIFIVE_SPI_REG_CSDEF);
+	if (!cs_bits) {
+		dev_warn(dev, "Could not auto probe CS lines\n");
+		return;
+	}
+
+	spi->ctlr.num_chipselect = ilog2(cs_bits) + 1;
+	if (spi->ctlr.num_chipselect > SIFIVE_SPI_MAX_CS) {
+		dev_warn(dev, "Invalid number of spi slaves\n");
+		return;
+	}
+
+	/* Watermark interrupts are disabled by default */
+	writel(0, spi->regs + SIFIVE_SPI_REG_IE);
+
+	/* Default watermark FIFO threshold values */
+	writel(1, spi->regs + SIFIVE_SPI_REG_TXMARK);
+	writel(0, spi->regs + SIFIVE_SPI_REG_RXMARK);
+
+	/* Set CS/SCK Delays and Inactive Time to defaults */
+	writel(SIFIVE_SPI_DELAY0_CSSCK(1) | SIFIVE_SPI_DELAY0_SCKCS(1),
+	       spi->regs + SIFIVE_SPI_REG_DELAY0);
+	writel(SIFIVE_SPI_DELAY1_INTERCS(1) | SIFIVE_SPI_DELAY1_INTERXFR(0),
+	       spi->regs + SIFIVE_SPI_REG_DELAY1);
+
+	/* Exit specialized memory-mapped SPI flash mode */
+	writel(0, spi->regs + SIFIVE_SPI_REG_FCTRL);
+}
+
+static const struct spi_controller_mem_ops sifive_spi_mem_ops = {
+	.exec_op	= sifive_spi_exec_op,
+};
+
+static void sifive_spi_dt_probe(struct sifive_spi *spi)
+{
+	struct device_node *node = spi->ctlr.dev->device_node;
+
+	spi->fifo_depth = SIFIVE_SPI_DEFAULT_DEPTH;
+	of_property_read_u32(node, "sifive,fifo-depth", &spi->fifo_depth);
+
+	spi->bits_per_word = SIFIVE_SPI_DEFAULT_BITS;
+	of_property_read_u32(node, "sifive,max-bits-per-word", &spi->bits_per_word);
+}
+
+static int sifive_spi_probe(struct device_d *dev)
+{
+	struct sifive_spi *spi;
+	struct resource *iores;
+	struct spi_controller *ctlr;
+	struct clk *clkdev;
+
+	iores = dev_request_mem_resource(dev, 0);
+	if (IS_ERR(iores))
+		return PTR_ERR(iores);
+
+	spi = xzalloc(sizeof(*spi));
+
+	spi->regs = IOMEM(iores->start);
+	if (!spi->regs)
+		return -ENODEV;
+
+	ctlr = &spi->ctlr;
+	ctlr->dev = dev;
+
+	ctlr->setup = sifive_spi_setup;
+	ctlr->transfer = sifive_spi_transfer;
+	ctlr->mem_ops = &sifive_spi_mem_ops;
+
+	ctlr->bus_num = -1;
+
+	spi_controller_set_devdata(ctlr, spi);
+
+	sifive_spi_dt_probe(spi);
+
+	clkdev = clk_get(dev, NULL);
+	if (IS_ERR(clkdev))
+		return PTR_ERR(clkdev);
+
+	spi->freq = clk_get_rate(clkdev);
+
+	/* init the sifive spi hw */
+	sifive_spi_init_hw(spi);
+
+	return spi_register_master(ctlr);
+}
+
+static const struct of_device_id sifive_spi_ids[] = {
+	{ .compatible = "sifive,spi0" },
+	{ /* sentinel */ }
+};
+
+static struct driver_d sifive_spi_driver = {
+	.name  = "sifive_spi",
+	.probe = sifive_spi_probe,
+	.of_compatible = sifive_spi_ids,
+};
+coredevice_platform_driver(sifive_spi_driver);
-- 
2.34.1


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