spi/xlp: SPI controller driver for Netlogic XLP SoCs

Add SPI Master controller driver for the SPI interface on XLP8XX,
XLP3XX, XLP2XX, XLP9XX and XLP5XX family of Netlogic XLP MIPS64 processors.

Signed-off-by: Kamlakant Patel <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

drivers/spi/Kconfig

···
 
 	  Or for the DS570, see "XPS Serial Peripheral Interface (SPI) (v2.00b)"
 
+config SPI_XLP
+	tristate "Netlogic XLP SPI controller driver"
+	depends on CPU_XLP || COMPILE_TEST
+	help
+	  Enable support for the SPI controller on the Netlogic XLP SoCs.
+	  Currently supported XLP variants are XLP8XX, XLP3XX, XLP2XX, XLP9XX
+	  and XLP5XX.
+
+	  If you have a Netlogic XLP platform say Y here.
+	  If unsure, say N.
+
 config SPI_XTENSA_XTFPGA
 	tristate "Xtensa SPI controller for xtfpga"
 	depends on (XTENSA && XTENSA_PLATFORM_XTFPGA) || COMPILE_TEST

drivers/spi/Makefile

···
 obj-$(CONFIG_SPI_TXX9)			+= spi-txx9.o
 obj-$(CONFIG_SPI_XCOMM)		+= spi-xcomm.o
 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

drivers/spi/spi-xlp.c

···
+/*
+ * Copyright (C) 2003-2015 Broadcom Corporation
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 (GPL v2)
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include <linux/clk.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/of.h>
+#include <linux/interrupt.h>
+
+/* SPI Configuration Register */
+#define XLP_SPI_CONFIG			0x00
+#define XLP_SPI_CPHA			BIT(0)
+#define XLP_SPI_CPOL			BIT(1)
+#define XLP_SPI_CS_POL			BIT(2)
+#define XLP_SPI_TXMISO_EN		BIT(3)
+#define XLP_SPI_TXMOSI_EN		BIT(4)
+#define XLP_SPI_RXMISO_EN		BIT(5)
+#define XLP_SPI_CS_LSBFE		BIT(10)
+#define XLP_SPI_RXCAP_EN		BIT(11)
+
+/* SPI Frequency Divider Register */
+#define XLP_SPI_FDIV			0x04
+
+/* SPI Command Register */
+#define XLP_SPI_CMD			0x08
+#define XLP_SPI_CMD_IDLE_MASK		0x0
+#define XLP_SPI_CMD_TX_MASK		0x1
+#define XLP_SPI_CMD_RX_MASK		0x2
+#define XLP_SPI_CMD_TXRX_MASK		0x3
+#define XLP_SPI_CMD_CONT		BIT(4)
+#define XLP_SPI_XFR_BITCNT_SHIFT	16
+
+/* SPI Status Register */
+#define XLP_SPI_STATUS			0x0c
+#define XLP_SPI_XFR_PENDING		BIT(0)
+#define XLP_SPI_XFR_DONE		BIT(1)
+#define XLP_SPI_TX_INT			BIT(2)
+#define XLP_SPI_RX_INT			BIT(3)
+#define XLP_SPI_TX_UF			BIT(4)
+#define XLP_SPI_RX_OF			BIT(5)
+#define XLP_SPI_STAT_MASK		0x3f
+
+/* SPI Interrupt Enable Register */
+#define XLP_SPI_INTR_EN			0x10
+#define XLP_SPI_INTR_DONE		BIT(0)
+#define XLP_SPI_INTR_TXTH		BIT(1)
+#define XLP_SPI_INTR_RXTH		BIT(2)
+#define XLP_SPI_INTR_TXUF		BIT(3)
+#define XLP_SPI_INTR_RXOF		BIT(4)
+
+/* SPI FIFO Threshold Register */
+#define XLP_SPI_FIFO_THRESH		0x14
+
+/* SPI FIFO Word Count Register */
+#define XLP_SPI_FIFO_WCNT		0x18
+#define XLP_SPI_RXFIFO_WCNT_MASK	0xf
+#define XLP_SPI_TXFIFO_WCNT_MASK	0xf0
+#define XLP_SPI_TXFIFO_WCNT_SHIFT	4
+
+/* SPI Transmit Data FIFO Register */
+#define XLP_SPI_TXDATA_FIFO		0x1c
+
+/* SPI Receive Data FIFO Register */
+#define XLP_SPI_RXDATA_FIFO		0x20
+
+/* SPI System Control Register */
+#define XLP_SPI_SYSCTRL			0x100
+#define XLP_SPI_SYS_RESET		BIT(0)
+#define XLP_SPI_SYS_CLKDIS		BIT(1)
+#define XLP_SPI_SYS_PMEN		BIT(8)
+
+#define SPI_CS_OFFSET			0x40
+#define XLP_SPI_TXRXTH			0x80
+#define XLP_SPI_FIFO_SIZE		8
+#define XLP_SPI_MAX_CS			4
+#define XLP_SPI_DEFAULT_FREQ		133333333
+#define XLP_SPI_FDIV_MIN		4
+#define XLP_SPI_FDIV_MAX		65535
+/*
+ * SPI can transfer only 28 bytes properly at a time. So split the
+ * transfer into 28 bytes size.
+ */
+#define XLP_SPI_XFER_SIZE		28
+
+struct xlp_spi_priv {
+	struct device		dev;		/* device structure */
+	void __iomem		*base;		/* spi registers base address */
+	const u8		*tx_buf;	/* tx data buffer */
+	u8			*rx_buf;	/* rx data buffer */
+	int			tx_len;		/* tx xfer length */
+	int			rx_len;		/* rx xfer length */
+	int			txerrors;	/* TXFIFO underflow count */
+	int			rxerrors;	/* RXFIFO overflow count */
+	int			cs;		/* slave device chip select */
+	u32			spi_clk;	/* spi clock frequency */
+	bool			cmd_cont;	/* cs active */
+	struct completion	done;		/* completion notification */
+};
+
+static inline u32 xlp_spi_reg_read(struct xlp_spi_priv *priv,
+				int cs, int regoff)
+{
+	return readl(priv->base + regoff + cs * SPI_CS_OFFSET);
+}
+
+static inline void xlp_spi_reg_write(struct xlp_spi_priv *priv, int cs,
+				int regoff, u32 val)
+{
+	writel(val, priv->base + regoff + cs * SPI_CS_OFFSET);
+}
+
+static inline void xlp_spi_sysctl_write(struct xlp_spi_priv *priv,
+				int regoff, u32 val)
+{
+	writel(val, priv->base + regoff);
+}
+
+/*
+ * Setup global SPI_SYSCTRL register for all SPI channels.
+ */
+static void xlp_spi_sysctl_setup(struct xlp_spi_priv *xspi)
+{
+	int cs;
+
+	for (cs = 0; cs < XLP_SPI_MAX_CS; cs++)
+		xlp_spi_sysctl_write(xspi, XLP_SPI_SYSCTRL,
+				XLP_SPI_SYS_RESET << cs);
+	xlp_spi_sysctl_write(xspi, XLP_SPI_SYSCTRL, XLP_SPI_SYS_PMEN);
+}
+
+static int xlp_spi_setup(struct spi_device *spi)
+{
+	struct xlp_spi_priv *xspi;
+	u32 fdiv, cfg;
+	int cs;
+
+	xspi = spi_master_get_devdata(spi->master);
+	cs = spi->chip_select;
+	/*
+	 * The value of fdiv must be between 4 and 65535.
+	 */
+	fdiv = DIV_ROUND_UP(xspi->spi_clk, spi->max_speed_hz);
+	if (fdiv > XLP_SPI_FDIV_MAX)
+		fdiv = XLP_SPI_FDIV_MAX;
+	else if (fdiv < XLP_SPI_FDIV_MIN)
+		fdiv = XLP_SPI_FDIV_MIN;
+
+	xlp_spi_reg_write(xspi, cs, XLP_SPI_FDIV, fdiv);
+	xlp_spi_reg_write(xspi, cs, XLP_SPI_FIFO_THRESH, XLP_SPI_TXRXTH);
+	cfg = xlp_spi_reg_read(xspi, cs, XLP_SPI_CONFIG);
+	if (spi->mode & SPI_CPHA)
+		cfg |= XLP_SPI_CPHA;
+	else
+		cfg &= ~XLP_SPI_CPHA;
+	if (spi->mode & SPI_CPOL)
+		cfg |= XLP_SPI_CPOL;
+	else
+		cfg &= ~XLP_SPI_CPOL;
+	if (!(spi->mode & SPI_CS_HIGH))
+		cfg |= XLP_SPI_CS_POL;
+	else
+		cfg &= ~XLP_SPI_CS_POL;
+	if (spi->mode & SPI_LSB_FIRST)
+		cfg |= XLP_SPI_CS_LSBFE;
+	else
+		cfg &= ~XLP_SPI_CS_LSBFE;
+
+	cfg |= XLP_SPI_TXMOSI_EN | XLP_SPI_RXMISO_EN;
+	if (fdiv == 4)
+		cfg |= XLP_SPI_RXCAP_EN;
+	xlp_spi_reg_write(xspi, cs, XLP_SPI_CONFIG, cfg);
+
+	return 0;
+}
+
+static void xlp_spi_read_rxfifo(struct xlp_spi_priv *xspi)
+{
+	u32 rx_data, rxfifo_cnt;
+	int i, j, nbytes;
+
+	rxfifo_cnt = xlp_spi_reg_read(xspi, xspi->cs, XLP_SPI_FIFO_WCNT);
+	rxfifo_cnt &= XLP_SPI_RXFIFO_WCNT_MASK;
+	while (rxfifo_cnt) {
+		rx_data = xlp_spi_reg_read(xspi, xspi->cs, XLP_SPI_RXDATA_FIFO);
+		j = 0;
+		nbytes = min(xspi->rx_len, 4);
+		for (i = nbytes - 1; i >= 0; i--, j++)
+			xspi->rx_buf[i] = (rx_data >> (j * 8)) & 0xff;
+
+		xspi->rx_len -= nbytes;
+		xspi->rx_buf += nbytes;
+		rxfifo_cnt--;
+	}
+}
+
+static void xlp_spi_fill_txfifo(struct xlp_spi_priv *xspi)
+{
+	u32 tx_data, txfifo_cnt;
+	int i, j, nbytes;
+
+	txfifo_cnt = xlp_spi_reg_read(xspi, xspi->cs, XLP_SPI_FIFO_WCNT);
+	txfifo_cnt &= XLP_SPI_TXFIFO_WCNT_MASK;
+	txfifo_cnt >>= XLP_SPI_TXFIFO_WCNT_SHIFT;
+	while (xspi->tx_len && (txfifo_cnt < XLP_SPI_FIFO_SIZE)) {
+		j = 0;
+		tx_data = 0;
+		nbytes = min(xspi->tx_len, 4);
+		for (i = nbytes - 1; i >= 0; i--, j++)
+			tx_data |= xspi->tx_buf[i] << (j * 8);
+
+		xlp_spi_reg_write(xspi, xspi->cs, XLP_SPI_TXDATA_FIFO, tx_data);
+		xspi->tx_len -= nbytes;
+		xspi->tx_buf += nbytes;
+		txfifo_cnt++;
+	}
+}
+
+static irqreturn_t xlp_spi_interrupt(int irq, void *dev_id)
+{
+	struct xlp_spi_priv *xspi = dev_id;
+	u32 stat;
+
+	stat = xlp_spi_reg_read(xspi, xspi->cs, XLP_SPI_STATUS) &
+		XLP_SPI_STAT_MASK;
+	if (!stat)
+		return IRQ_NONE;
+
+	if (stat & XLP_SPI_TX_INT) {
+		if (xspi->tx_len)
+			xlp_spi_fill_txfifo(xspi);
+		if (stat & XLP_SPI_TX_UF)
+			xspi->txerrors++;
+	}
+
+	if (stat & XLP_SPI_RX_INT) {
+		if (xspi->rx_len)
+			xlp_spi_read_rxfifo(xspi);
+		if (stat & XLP_SPI_RX_OF)
+			xspi->rxerrors++;
+	}
+
+	/* write status back to clear interrupts */
+	xlp_spi_reg_write(xspi, xspi->cs, XLP_SPI_STATUS, stat);
+	if (stat & XLP_SPI_XFR_DONE)
+		complete(&xspi->done);
+
+	return IRQ_HANDLED;
+}
+
+static void xlp_spi_send_cmd(struct xlp_spi_priv *xspi, int xfer_len,
+			int cmd_cont)
+{
+	u32 cmd = 0;
+
+	if (xspi->tx_buf)
+		cmd |= XLP_SPI_CMD_TX_MASK;
+	if (xspi->rx_buf)
+		cmd |= XLP_SPI_CMD_RX_MASK;
+	if (cmd_cont)
+		cmd |= XLP_SPI_CMD_CONT;
+	cmd |= ((xfer_len * 8 - 1) << XLP_SPI_XFR_BITCNT_SHIFT);
+	xlp_spi_reg_write(xspi, xspi->cs, XLP_SPI_CMD, cmd);
+}
+
+static int xlp_spi_xfer_block(struct  xlp_spi_priv *xs,
+		const unsigned char *tx_buf,
+		unsigned char *rx_buf, int xfer_len, int cmd_cont)
+{
+	int timeout;
+	u32 intr_mask = 0;
+
+	xs->tx_buf = tx_buf;
+	xs->rx_buf = rx_buf;
+	xs->tx_len = (xs->tx_buf == NULL) ? 0 : xfer_len;
+	xs->rx_len = (xs->rx_buf == NULL) ? 0 : xfer_len;
+	xs->txerrors = xs->rxerrors = 0;
+
+	/* fill TXDATA_FIFO, then send the CMD */
+	if (xs->tx_len)
+		xlp_spi_fill_txfifo(xs);
+
+	xlp_spi_send_cmd(xs, xfer_len, cmd_cont);
+
+	/*
+	 * We are getting some spurious tx interrupts, so avoid enabling
+	 * tx interrupts when only rx is in process.
+	 * Enable all the interrupts in tx case.
+	 */
+	if (xs->tx_len)
+		intr_mask |= XLP_SPI_INTR_TXTH | XLP_SPI_INTR_TXUF |
+				XLP_SPI_INTR_RXTH | XLP_SPI_INTR_RXOF;
+	else
+		intr_mask |= XLP_SPI_INTR_RXTH | XLP_SPI_INTR_RXOF;
+
+	intr_mask |= XLP_SPI_INTR_DONE;
+	xlp_spi_reg_write(xs, xs->cs, XLP_SPI_INTR_EN, intr_mask);
+
+	timeout = wait_for_completion_timeout(&xs->done,
+				msecs_to_jiffies(1000));
+	/* Disable interrupts */
+	xlp_spi_reg_write(xs, xs->cs, XLP_SPI_INTR_EN, 0x0);
+	if (!timeout) {
+		dev_err(&xs->dev, "xfer timedout!\n");
+		goto out;
+	}
+	if (xs->txerrors || xs->rxerrors)
+		dev_err(&xs->dev, "Over/Underflow rx %d tx %d xfer %d!\n",
+				xs->rxerrors, xs->txerrors, xfer_len);
+
+	return xfer_len;
+out:
+	return -ETIMEDOUT;
+}
+
+static int xlp_spi_txrx_bufs(struct xlp_spi_priv *xs, struct spi_transfer *t)
+{
+	int bytesleft, sz;
+	unsigned char *rx_buf;
+	const unsigned char *tx_buf;
+
+	tx_buf = t->tx_buf;
+	rx_buf = t->rx_buf;
+	bytesleft = t->len;
+	while (bytesleft) {
+		if (bytesleft > XLP_SPI_XFER_SIZE)
+			sz = xlp_spi_xfer_block(xs, tx_buf, rx_buf,
+					XLP_SPI_XFER_SIZE, 1);
+		else
+			sz = xlp_spi_xfer_block(xs, tx_buf, rx_buf,
+					bytesleft, xs->cmd_cont);
+		if (sz < 0)
+			return sz;
+		bytesleft -= sz;
+		if (tx_buf)
+			tx_buf += sz;
+		if (rx_buf)
+			rx_buf += sz;
+	}
+	return bytesleft;
+}
+
+static int xlp_spi_transfer_one(struct spi_master *master,
+					struct spi_device *spi,
+					struct spi_transfer *t)
+{
+	struct xlp_spi_priv *xspi = spi_master_get_devdata(master);
+	int ret = 0;
+
+	xspi->cs = spi->chip_select;
+	xspi->dev = spi->dev;
+
+	if (spi_transfer_is_last(master, t))
+		xspi->cmd_cont = 0;
+	else
+		xspi->cmd_cont = 1;
+
+	if (xlp_spi_txrx_bufs(xspi, t))
+		ret = -EIO;
+
+	spi_finalize_current_transfer(master);
+	return ret;
+}
+
+static int xlp_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct xlp_spi_priv *xspi;
+	struct resource *res;
+	struct clk *clk;
+	int irq, err;
+
+	xspi = devm_kzalloc(&pdev->dev, sizeof(*xspi), GFP_KERNEL);
+	if (!xspi)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	xspi->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(xspi->base))
+		return PTR_ERR(xspi->base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "no IRQ resource found\n");
+		return -EINVAL;
+	}
+	err = devm_request_irq(&pdev->dev, irq, xlp_spi_interrupt, 0,
+			pdev->name, xspi);
+	if (err) {
+		dev_err(&pdev->dev, "unable to request irq %d\n", irq);
+		return err;
+	}
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "could not get spi clock\n");
+		return -ENODEV;
+	}
+	xspi->spi_clk = clk_get_rate(clk);
+
+	master = spi_alloc_master(&pdev->dev, 0);
+	if (!master) {
+		dev_err(&pdev->dev, "could not alloc master\n");
+		return -ENOMEM;
+	}
+
+	master->bus_num = 0;
+	master->num_chipselect = XLP_SPI_MAX_CS;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+	master->setup = xlp_spi_setup;
+	master->transfer_one = xlp_spi_transfer_one;
+	master->dev.of_node = pdev->dev.of_node;
+
+	init_completion(&xspi->done);
+	spi_master_set_devdata(master, xspi);
+	xlp_spi_sysctl_setup(xspi);
+
+	/* register spi controller */
+	err = devm_spi_register_master(&pdev->dev, master);
+	if (err) {
+		dev_err(&pdev->dev, "spi register master failed!\n");
+		spi_master_put(master);
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id xlp_spi_dt_id[] = {
+	{ .compatible = "netlogic,xlp832-spi" },
+	{ },
+};
+
+static struct platform_driver xlp_spi_driver = {
+	.probe	= xlp_spi_probe,
+	.driver = {
+		.name	= "xlp-spi",
+		.of_match_table = xlp_spi_dt_id,
+	},
+};
+module_platform_driver(xlp_spi_driver);
+
+MODULE_AUTHOR("Kamlakant Patel <[e-mail]>");
+MODULE_DESCRIPTION("Netlogic XLP SPI controller driver");
+MODULE_LICENSE("GPL v2");