Message-ID: <20251103160515.412706-4-prajna.rajendrakumar@microchip.com>
Date: Mon, 3 Nov 2025 16:05:15 +0000
From: Prajna Rajendra Kumar <prajna.rajendrakumar@...rochip.com>
To: Mark Brown <broonie@...nel.org>
CC: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	<linux-riscv@...ts.infradead.org>, <linux-spi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>, Conor Dooley
	<conor.dooley@...rochip.com>, Daire McNamara <daire.mcnamara@...rochip.com>,
	Valentina Fernandez Alanis <valentina.fernandezalanis@...rochip.com>, "Cyril
 Jean" <cyril.jean@...rochip.com>, Prajna Rajendra Kumar
	<prajna.rajendrakumar@...rochip.com>
Subject: [PATCH v1 3/3] spi: add support for microchip "soft" spi controller

Introduce driver support for the Microchip FPGA CoreSPI IP.

This driver supports only the Motorola SPI mode. TI and NSC modes are
not currently supported.

Signed-off-by: Prajna Rajendra Kumar <prajna.rajendrakumar@...rochip.com>
---
 drivers/spi/Kconfig              |   9 +
 drivers/spi/Makefile             |   1 +
 drivers/spi/spi-microchip-core.c | 443 +++++++++++++++++++++++++++++++
 3 files changed, 453 insertions(+)
 create mode 100644 drivers/spi/spi-microchip-core.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index d53798036076..d24b118f90cd 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -706,6 +706,15 @@ config SPI_MESON_SPIFC
 	  This enables master mode support for the SPIFC (SPI flash
 	  controller) available in Amlogic Meson SoCs.
 
+config SPI_MICROCHIP_CORE
+	tristate "Microchip FPGA SPI controllers"
+	depends on SPI_MASTER
+	help
+	  This enables the SPI driver for Microchip FPGA SPI controllers.
+	  Say Y or M here if you want to use the "soft" controllers on
+	  PolarFire SoC.
+	  If built as a module, it will be called spi-microchip-core.
+
 config SPI_MICROCHIP_CORE_QSPI
 	tristate "Microchip FPGA QSPI controllers"
 	depends on SPI_MASTER
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 1f7c06a3091d..479a88882020 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -86,6 +86,7 @@ obj-$(CONFIG_SPI_LOONGSON_PLATFORM)	+= spi-loongson-plat.o
 obj-$(CONFIG_SPI_LP8841_RTC)		+= spi-lp8841-rtc.o
 obj-$(CONFIG_SPI_MESON_SPICC)		+= spi-meson-spicc.o
 obj-$(CONFIG_SPI_MESON_SPIFC)		+= spi-meson-spifc.o
+obj-$(CONFIG_SPI_MICROCHIP_CORE)	+= spi-microchip-core.o
 obj-$(CONFIG_SPI_MICROCHIP_CORE_QSPI)	+= spi-microchip-core-qspi.o
 obj-$(CONFIG_SPI_MPC512x_PSC)		+= spi-mpc512x-psc.o
 obj-$(CONFIG_SPI_MPC52xx_PSC)		+= spi-mpc52xx-psc.o
diff --git a/drivers/spi/spi-microchip-core.c b/drivers/spi/spi-microchip-core.c
new file mode 100644
index 000000000000..8fb919e899b8
--- /dev/null
+++ b/drivers/spi/spi-microchip-core.c
@@ -0,0 +1,443 @@
+// SPDX-License-Identifier: (GPL-2.0)
+//
+// Microchip CoreSPI controller driver
+//
+// Copyright (c) 2025 Microchip Technology Inc. and its subsidiaries
+//
+// Author: Prajna Rajendra Kumar <prajna.rajendrakumar@...rochip.com>
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+
+#define MCHP_CORESPI_MAX_CS				(8)
+#define MCHP_CORESPI_DEFAULT_FIFO_DEPTH			(4)
+#define MCHP_CORESPI_DEFAULT_MOTOROLA_MODE		(3)
+
+#define MCHP_CORESPI_CONTROL_ENABLE			BIT(0)
+#define MCHP_CORESPI_CONTROL_MASTER			BIT(1)
+#define MCHP_CORESPI_CONTROL_TX_DATA_INT		BIT(3)
+#define MCHP_CORESPI_CONTROL_RX_OVER_INT		BIT(4)
+#define MCHP_CORESPI_CONTROL_TX_UNDER_INT		BIT(5)
+#define MCHP_CORESPI_CONTROL_FRAMEURUN			BIT(6)
+#define MCHP_CORESPI_CONTROL_OENOFF			BIT(7)
+
+#define MCHP_CORESPI_STATUS_ACTIVE			BIT(7)
+#define MCHP_CORESPI_STATUS_SSEL			BIT(6)
+#define MCHP_CORESPI_STATUS_TXFIFO_UNDERFLOW		BIT(5)
+#define MCHP_CORESPI_STATUS_RXFIFO_FULL			BIT(4)
+#define MCHP_CORESPI_STATUS_TXFIFO_FULL			BIT(3)
+#define MCHP_CORESPI_STATUS_RXFIFO_EMPTY		BIT(2)
+#define MCHP_CORESPI_STATUS_DONE			BIT(1)
+#define MCHP_CORESPI_STATUS_FIRSTFRAME			BIT(0)
+
+#define MCHP_CORESPI_INT_TXDONE				BIT(0)
+#define MCHP_CORESPI_INT_RX_CHANNEL_OVERFLOW		BIT(2)
+#define MCHP_CORESPI_INT_TX_CHANNEL_UNDERRUN		BIT(3)
+#define MCHP_CORESPI_INT_CMDINT				BIT(4)
+#define MCHP_CORESPI_INT_SSEND				BIT(5)
+#define MCHP_CORESPI_INT_DATA_RX			BIT(6)
+#define MCHP_CORESPI_INT_TXRFM				BIT(7)
+
+#define MCHP_CORESPI_CONTROL2_INTEN_TXRFMT		BIT(7)
+#define MCHP_CORESPI_CONTROL2_INTEN_DATA_RX		BIT(6)
+#define MCHP_CORESPI_CONTROL2_INTEN_SSEND		BIT(5)
+#define MCHP_CORESPI_CONTROL2_INTEN_CMD			BIT(4)
+
+#define INT_ENABLE_MASK (MCHP_CORESPI_CONTROL_TX_DATA_INT | MCHP_CORESPI_CONTROL_RX_OVER_INT | \
+			 MCHP_CORESPI_CONTROL_TX_UNDER_INT)
+
+#define MCHP_CORESPI_REG_CONTROL			(0x00)
+#define MCHP_CORESPI_REG_INTCLEAR			(0x04)
+#define MCHP_CORESPI_REG_RXDATA				(0x08)
+#define MCHP_CORESPI_REG_TXDATA				(0x0c)
+#define MCHP_CORESPI_REG_INTMASK			(0X10)
+#define MCHP_CORESPI_REG_INTRAW				(0X14)
+#define MCHP_CORESPI_REG_CONTROL2			(0x18)
+#define MCHP_CORESPI_REG_COMMAND			(0x1c)
+#define MCHP_CORESPI_REG_STAT				(0x20)
+#define MCHP_CORESPI_REG_SSEL				(0x24)
+#define MCHP_CORESPI_REG_TXDATA_LAST			(0X28)
+#define MCHP_CORESPI_REG_CLK_DIV			(0x2c)
+
+struct mchp_corespi {
+	void __iomem *regs;
+	struct clk *clk;
+	const u8 *tx_buf;
+	u8 *rx_buf;
+	u32 clk_gen;
+	int irq;
+	int tx_len;
+	int rx_len;
+	u32 fifo_depth;
+};
+
+static inline void mchp_corespi_disable(struct mchp_corespi *spi)
+{
+	u8 control = readb(spi->regs + MCHP_CORESPI_REG_CONTROL);
+
+	control &= ~MCHP_CORESPI_CONTROL_ENABLE;
+
+	writeb(control, spi->regs + MCHP_CORESPI_REG_CONTROL);
+}
+
+static inline void mchp_corespi_read_fifo(struct mchp_corespi *spi, u32 fifo_max)
+{
+	for (int i = 0; i < fifo_max; i++) {
+		u32 data;
+
+		while (readb(spi->regs + MCHP_CORESPI_REG_STAT) &
+		       MCHP_CORESPI_STATUS_RXFIFO_EMPTY)
+			;
+
+		data = readb(spi->regs + MCHP_CORESPI_REG_RXDATA);
+
+		spi->rx_len--;
+		if (!spi->rx_buf)
+			continue;
+
+		*spi->rx_buf = data;
+
+		spi->rx_buf++;
+	}
+}
+
+static void mchp_corespi_enable_ints(struct mchp_corespi *spi)
+{
+	u8 control = readb(spi->regs + MCHP_CORESPI_REG_CONTROL);
+
+	control |= INT_ENABLE_MASK;
+	writeb(control, spi->regs + MCHP_CORESPI_REG_CONTROL);
+}
+
+static void mchp_corespi_disable_ints(struct mchp_corespi *spi)
+{
+	u8 control = readb(spi->regs + MCHP_CORESPI_REG_CONTROL);
+
+	control &= ~INT_ENABLE_MASK;
+	writeb(control, spi->regs + MCHP_CORESPI_REG_CONTROL);
+}
+
+static inline void mchp_corespi_write_fifo(struct mchp_corespi *spi, u32 fifo_max)
+{
+	int i = 0;
+
+	while ((i < fifo_max) &&
+	       !(readb(spi->regs + MCHP_CORESPI_REG_STAT) &
+		 MCHP_CORESPI_STATUS_TXFIFO_FULL)) {
+		u32 word;
+
+		word = spi->tx_buf ? *spi->tx_buf : 0xaa;
+		writeb(word, spi->regs + MCHP_CORESPI_REG_TXDATA);
+
+		if (spi->tx_buf)
+			spi->tx_buf++;
+
+		i++;
+	}
+
+	spi->tx_len -= i;
+}
+
+static void mchp_corespi_set_cs(struct spi_device *spi, bool disable)
+{
+	struct mchp_corespi *corespi = spi_controller_get_devdata(spi->controller);
+	u32 reg;
+
+	reg = readb(corespi->regs + MCHP_CORESPI_REG_SSEL);
+	reg &= ~BIT(spi_get_chipselect(spi, 0));
+	reg |= !disable << spi_get_chipselect(spi, 0);
+
+	writeb(reg, corespi->regs + MCHP_CORESPI_REG_SSEL);
+}
+
+static int mchp_corespi_setup(struct spi_device *spi)
+{
+	struct mchp_corespi *corespi = spi_controller_get_devdata(spi->controller);
+	u32 dev_mode = spi->mode & (SPI_CPOL | SPI_CPHA);
+
+	if (spi_get_csgpiod(spi, 0))
+		return 0;
+
+	if (spi->mode & (SPI_CS_HIGH)) {
+		dev_err(&spi->dev, "unable to support active-high CS in Motorola mode\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (dev_mode & ~spi->controller->mode_bits) {
+		dev_err(&spi->dev, "incompatible CPOL/CPHA, must match controller's Motorola mode\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void mchp_corespi_init(struct spi_controller *host, struct mchp_corespi *spi)
+{
+	u8 control = readb(spi->regs + MCHP_CORESPI_REG_CONTROL);
+
+	/* Master mode changes require core to be disabled.*/
+	control = (control & ~MCHP_CORESPI_CONTROL_ENABLE) | MCHP_CORESPI_CONTROL_MASTER;
+
+	writeb(control, spi->regs + MCHP_CORESPI_REG_CONTROL);
+
+	mchp_corespi_enable_ints(spi);
+
+	control = readb(spi->regs + MCHP_CORESPI_REG_CONTROL);
+	control |= MCHP_CORESPI_CONTROL_ENABLE;
+
+	writeb(control, spi->regs + MCHP_CORESPI_REG_CONTROL);
+}
+
+static irqreturn_t mchp_corespi_interrupt(int irq, void *dev_id)
+{
+	struct spi_controller *host = dev_id;
+	struct mchp_corespi *spi = spi_controller_get_devdata(host);
+	u8 intfield = readb(spi->regs + MCHP_CORESPI_REG_INTMASK) & 0xff;
+	bool finalise = false;
+
+	/* Interrupt line may be shared and not for us at all */
+	if (intfield == 0)
+		return IRQ_NONE;
+
+	if (intfield & MCHP_CORESPI_INT_TXDONE)
+		writeb(MCHP_CORESPI_INT_TXDONE, spi->regs + MCHP_CORESPI_REG_INTCLEAR);
+
+	if (intfield & MCHP_CORESPI_INT_RX_CHANNEL_OVERFLOW) {
+		writeb(MCHP_CORESPI_INT_RX_CHANNEL_OVERFLOW,
+		       spi->regs + MCHP_CORESPI_REG_INTCLEAR);
+		finalise = true;
+		dev_err(&host->dev,
+			"RX OVERFLOW: rxlen: %d, txlen: %d\n",
+			spi->rx_len, spi->tx_len);
+	}
+
+	if (intfield & MCHP_CORESPI_INT_TX_CHANNEL_UNDERRUN) {
+		writeb(MCHP_CORESPI_INT_TX_CHANNEL_UNDERRUN,
+		       spi->regs + MCHP_CORESPI_REG_INTCLEAR);
+		finalise = true;
+		dev_err(&host->dev,
+			"TX UNDERFLOW: rxlen: %d, txlen: %d\n",
+			spi->rx_len, spi->tx_len);
+	}
+
+	if (finalise)
+		spi_finalize_current_transfer(host);
+
+	return IRQ_HANDLED;
+}
+
+static int mchp_corespi_set_clk_div(struct mchp_corespi *spi,
+				    unsigned long target_hz)
+{
+	unsigned long pclk_hz, spi_hz;
+	u32 clk_div;
+
+	/* Get peripheral clock rate */
+	pclk_hz = clk_get_rate(spi->clk);
+	if (!pclk_hz)
+		return -EINVAL;
+
+	/*
+	 * Calculate clock rate generated by SPI master
+	 * Formula: SPICLK = PCLK / (2 * (CLK_DIV + 1))
+	 */
+	clk_div = DIV_ROUND_UP(pclk_hz, 2 * target_hz) - 1;
+
+	if (clk_div > 0xFF)
+		return -EINVAL;
+
+	spi_hz = pclk_hz / (2 * (clk_div + 1));
+
+	if (spi_hz > target_hz)
+		return -EINVAL;
+
+	writeb(clk_div, spi->regs + MCHP_CORESPI_REG_CLK_DIV);
+
+	return 0;
+}
+
+static int mchp_corespi_transfer_one(struct spi_controller *host,
+				     struct spi_device *spi_dev,
+				     struct spi_transfer *xfer)
+{
+	struct mchp_corespi *spi = spi_controller_get_devdata(host);
+	int ret;
+
+	ret = mchp_corespi_set_clk_div(spi, (unsigned long)xfer->speed_hz);
+	if (ret) {
+		dev_err(&host->dev, "failed to set clock divider for target %u Hz\n",
+			xfer->speed_hz);
+		return ret;
+	}
+
+	spi->tx_buf = xfer->tx_buf;
+	spi->rx_buf = xfer->rx_buf;
+	spi->tx_len = xfer->len;
+	spi->rx_len = xfer->len;
+
+	while (spi->tx_len) {
+		int fifo_max = min_t(int, spi->tx_len, spi->fifo_depth);
+
+		mchp_corespi_write_fifo(spi, fifo_max);
+		mchp_corespi_read_fifo(spi, fifo_max);
+	}
+
+	spi_finalize_current_transfer(host);
+	return 1;
+}
+
+static int mchp_corespi_probe(struct platform_device *pdev)
+{
+	struct spi_controller *host;
+	struct mchp_corespi *spi;
+	struct resource *res;
+	const char *protocol;
+	u32 num_cs, mode, frame_size;
+	bool assert_ssel;
+	int ret = 0;
+
+	host = devm_spi_alloc_host(&pdev->dev, sizeof(*spi));
+	if (!host)
+		return dev_err_probe(&pdev->dev, -ENOMEM,
+				     "unable to allocate host for SPI controller\n");
+
+	platform_set_drvdata(pdev, host);
+
+	if (of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs))
+		num_cs = MCHP_CORESPI_MAX_CS;
+
+	/*
+	 * Protocol: CFG_MODE
+	 * CoreSPI can be configured for Motorola, TI or NSC.
+	 * The current driver supports only Motorola mode.
+	 */
+	ret = of_property_read_string(pdev->dev.of_node, "microchip,protocol-configuration",
+				      &protocol);
+	if (strcmp(protocol, "motorola") != 0)
+		return dev_err_probe(&pdev->dev, -EINVAL,
+				     "CoreSPI: protocol '%s' not supported by this driver\n",
+				      protocol);
+
+	/*
+	 * Motorola mode (0-3): CFG_MOT_MODE
+	 * Mode is fixed in the IP configurator.
+	 */
+	ret = of_property_read_u32(pdev->dev.of_node, "microchip,motorola-mode", &mode);
+	if (ret)
+		mode = MCHP_CORESPI_DEFAULT_MOTOROLA_MODE;
+	else if (mode > 3)
+		return dev_err_probe(&pdev->dev, -EINVAL,
+				     "invalid 'microchip,motorola-mode' value %u\n", mode);
+
+	/*
+	 * Frame size: CFG_FRAME_SIZE
+	 * The hardware allows frame sizes <= APB data width.
+	 * However, this driver currently only supports 8-bit frames.
+	 */
+	ret = of_property_read_u32(pdev->dev.of_node, "microchip,frame-size", &frame_size);
+	if (!ret && frame_size != 8)
+		return dev_err_probe(&pdev->dev, -EINVAL,
+				     "CoreSPI: frame size %u not supported by this driver\n",
+				     frame_size);
+
+	/*
+	 * SSEL: CFG_MOT_SSEL
+	 * CoreSPI deasserts SSEL when the TX FIFO empties.
+	 * To prevent CS deassertion when TX FIFO drains, the ssel-active property
+	 * keeps CS asserted for the full SPI transfer.
+	 */
+	assert_ssel = of_property_read_bool(pdev->dev.of_node, "microchip,ssel-active");
+	if (!assert_ssel)
+		return dev_err_probe(&pdev->dev, -EINVAL,
+				     "hardware must enable 'microchip,ssel-active' to keep CS asserted for the SPI transfer\n");
+
+	spi = spi_controller_get_devdata(host);
+
+	host->num_chipselect = num_cs;
+	host->mode_bits = mode;
+	host->setup = mchp_corespi_setup;
+	host->use_gpio_descriptors = true;
+	host->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
+	host->transfer_one = mchp_corespi_transfer_one;
+	host->set_cs = mchp_corespi_set_cs;
+	host->dev.of_node = pdev->dev.of_node;
+
+	ret = of_property_read_u32(pdev->dev.of_node, "fifo-depth", &spi->fifo_depth);
+	if (ret)
+		spi->fifo_depth = MCHP_CORESPI_DEFAULT_FIFO_DEPTH;
+
+	spi->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(spi->regs))
+		return PTR_ERR(spi->regs);
+
+	spi->irq = platform_get_irq(pdev, 0);
+	if (spi->irq < 0)
+		return spi->irq;
+
+	ret = devm_request_irq(&pdev->dev, spi->irq, mchp_corespi_interrupt,
+			       IRQF_SHARED, dev_name(&pdev->dev), host);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret,
+				     "could not request irq\n");
+
+	spi->clk = devm_clk_get_enabled(&pdev->dev, NULL);
+	if (IS_ERR(spi->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(spi->clk),
+				     "could not get clk\n");
+
+	mchp_corespi_init(host, spi);
+
+	ret = devm_spi_register_controller(&pdev->dev, host);
+	if (ret) {
+		mchp_corespi_disable(spi);
+		return dev_err_probe(&pdev->dev, ret,
+				     "unable to register host for CoreSPI controller\n");
+	}
+
+	return 0;
+}
+
+static void mchp_corespi_remove(struct platform_device *pdev)
+{
+	struct spi_controller *host = platform_get_drvdata(pdev);
+	struct mchp_corespi *spi = spi_controller_get_devdata(host);
+
+	mchp_corespi_disable_ints(spi);
+	mchp_corespi_disable(spi);
+}
+
+#define MICROCHIP_SPI_PM_OPS (NULL)
+
+/*
+ * Platform driver data structure
+ */
+
+#if defined(CONFIG_OF)
+static const struct of_device_id mchp_corespi_dt_ids[] = {
+	{ .compatible = "microchip,corespi-rtl-v5" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mchp_corespi_dt_ids);
+#endif
+
+static struct platform_driver mchp_corespi_driver = {
+	.probe = mchp_corespi_probe,
+	.driver = {
+		.name = "microchip-corespi",
+		.pm = MICROCHIP_SPI_PM_OPS,
+		.of_match_table = of_match_ptr(mchp_corespi_dt_ids),
+	},
+	.remove_new = mchp_corespi_remove,
+};
+module_platform_driver(mchp_corespi_driver);
+MODULE_DESCRIPTION("Microchip CoreSPI controller driver");
+MODULE_AUTHOR("Prajna Rajendra Kumar <prajna.rajendrakumar@...rochip.com>");
+MODULE_LICENSE("GPL");
-- 
2.25.1

Powered by blists - more mailing lists