1 files changed, 499 insertions, 0 deletions
diff --git a/drivers/spi/spi-ppc4xx.c b/drivers/spi/spi-ppc4xx.c
new file mode 100644
index 000000000..d65f047b6
--- /dev/null
+++ b/drivers/spi/spi-ppc4xx.c
@@ -0,0 +1,499 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SPI_PPC4XX SPI controller driver.
+ *
+ * Copyright (C) 2007 Gary Jennejohn <garyj@denx.de>
+ * Copyright 2008 Stefan Roese <sr@denx.de>, DENX Software Engineering
+ * Copyright 2009 Harris Corporation, Steven A. Falco <sfalco@harris.com>
+ *
+ * Based in part on drivers/spi/spi_s3c24xx.c
+ *
+ * Copyright (c) 2006 Ben Dooks
+ * Copyright (c) 2006 Simtec Electronics
+ *	Ben Dooks <ben@simtec.co.uk>
+ */
+
+/*
+ * The PPC4xx SPI controller has no FIFO so each sent/received byte will
+ * generate an interrupt to the CPU. This can cause high CPU utilization.
+ * This driver allows platforms to reduce the interrupt load on the CPU
+ * during SPI transfers by setting max_speed_hz via the device tree.
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+
+#include <linux/io.h>
+#include <asm/dcr.h>
+#include <asm/dcr-regs.h>
+
+/* bits in mode register - bit 0 is MSb */
+
+/*
+ * SPI_PPC4XX_MODE_SCP = 0 means "data latched on trailing edge of clock"
+ * SPI_PPC4XX_MODE_SCP = 1 means "data latched on leading edge of clock"
+ * Note: This is the inverse of CPHA.
+ */
+#define SPI_PPC4XX_MODE_SCP	(0x80 >> 3)
+
+/* SPI_PPC4XX_MODE_SPE = 1 means "port enabled" */
+#define SPI_PPC4XX_MODE_SPE	(0x80 >> 4)
+
+/*
+ * SPI_PPC4XX_MODE_RD = 0 means "MSB first" - this is the normal mode
+ * SPI_PPC4XX_MODE_RD = 1 means "LSB first" - this is bit-reversed mode
+ * Note: This is identical to SPI_LSB_FIRST.
+ */
+#define SPI_PPC4XX_MODE_RD	(0x80 >> 5)
+
+/*
+ * SPI_PPC4XX_MODE_CI = 0 means "clock idles low"
+ * SPI_PPC4XX_MODE_CI = 1 means "clock idles high"
+ * Note: This is identical to CPOL.
+ */
+#define SPI_PPC4XX_MODE_CI	(0x80 >> 6)
+
+/*
+ * SPI_PPC4XX_MODE_IL = 0 means "loopback disable"
+ * SPI_PPC4XX_MODE_IL = 1 means "loopback enable"
+ */
+#define SPI_PPC4XX_MODE_IL	(0x80 >> 7)
+
+/* bits in control register */
+/* starts a transfer when set */
+#define SPI_PPC4XX_CR_STR	(0x80 >> 7)
+
+/* bits in status register */
+/* port is busy with a transfer */
+#define SPI_PPC4XX_SR_BSY	(0x80 >> 6)
+/* RxD ready */
+#define SPI_PPC4XX_SR_RBR	(0x80 >> 7)
+
+/* clock settings (SCP and CI) for various SPI modes */
+#define SPI_CLK_MODE0	(SPI_PPC4XX_MODE_SCP | 0)
+#define SPI_CLK_MODE1	(0 | 0)
+#define SPI_CLK_MODE2	(SPI_PPC4XX_MODE_SCP | SPI_PPC4XX_MODE_CI)
+#define SPI_CLK_MODE3	(0 | SPI_PPC4XX_MODE_CI)
+
+#define DRIVER_NAME	"spi_ppc4xx_of"
+
+struct spi_ppc4xx_regs {
+	u8 mode;
+	u8 rxd;
+	u8 txd;
+	u8 cr;
+	u8 sr;
+	u8 dummy;
+	/*
+	 * Clock divisor modulus register
+	 * This uses the following formula:
+	 *    SCPClkOut = OPBCLK/(4(CDM + 1))
+	 * or
+	 *    CDM = (OPBCLK/4*SCPClkOut) - 1
+	 * bit 0 is the MSb!
+	 */
+	u8 cdm;
+};
+
+/* SPI Controller driver's private data. */
+struct ppc4xx_spi {
+	/* bitbang has to be first */
+	struct spi_bitbang bitbang;
+	struct completion done;
+
+	u64 mapbase;
+	u64 mapsize;
+	int irqnum;
+	/* need this to set the SPI clock */
+	unsigned int opb_freq;
+
+	/* for transfers */
+	int len;
+	int count;
+	/* data buffers */
+	const unsigned char *tx;
+	unsigned char *rx;
+
+	struct spi_ppc4xx_regs __iomem *regs; /* pointer to the registers */
+	struct spi_master *master;
+	struct device *dev;
+};
+
+/* need this so we can set the clock in the chipselect routine */
+struct spi_ppc4xx_cs {
+	u8 mode;
+};
+
+static int spi_ppc4xx_txrx(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct ppc4xx_spi *hw;
+	u8 data;
+
+	dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
+		t->tx_buf, t->rx_buf, t->len);
+
+	hw = spi_master_get_devdata(spi->master);
+
+	hw->tx = t->tx_buf;
+	hw->rx = t->rx_buf;
+	hw->len = t->len;
+	hw->count = 0;
+
+	/* send the first byte */
+	data = hw->tx ? hw->tx[0] : 0;
+	out_8(&hw->regs->txd, data);
+	out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
+	wait_for_completion(&hw->done);
+
+	return hw->count;
+}
+
+static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
+	struct spi_ppc4xx_cs *cs = spi->controller_state;
+	int scr;
+	u8 cdm = 0;
+	u32 speed;
+	u8 bits_per_word;
+
+	/* Start with the generic configuration for this device. */
+	bits_per_word = spi->bits_per_word;
+	speed = spi->max_speed_hz;
+
+	/*
+	 * Modify the configuration if the transfer overrides it.  Do not allow
+	 * the transfer to overwrite the generic configuration with zeros.
+	 */
+	if (t) {
+		if (t->bits_per_word)
+			bits_per_word = t->bits_per_word;
+
+		if (t->speed_hz)
+			speed = min(t->speed_hz, spi->max_speed_hz);
+	}
+
+	if (!speed || (speed > spi->max_speed_hz)) {
+		dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed);
+		return -EINVAL;
+	}
+
+	/* Write new configuration */
+	out_8(&hw->regs->mode, cs->mode);
+
+	/* Set the clock */
+	/* opb_freq was already divided by 4 */
+	scr = (hw->opb_freq / speed) - 1;
+	if (scr > 0)
+		cdm = min(scr, 0xff);
+
+	dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", cdm, speed);
+
+	if (in_8(&hw->regs->cdm) != cdm)
+		out_8(&hw->regs->cdm, cdm);
+
+	mutex_lock(&hw->bitbang.lock);
+	if (!hw->bitbang.busy) {
+		hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
+		/* Need to ndelay here? */
+	}
+	mutex_unlock(&hw->bitbang.lock);
+
+	return 0;
+}
+
+static int spi_ppc4xx_setup(struct spi_device *spi)
+{
+	struct spi_ppc4xx_cs *cs = spi->controller_state;
+
+	if (!spi->max_speed_hz) {
+		dev_err(&spi->dev, "invalid max_speed_hz (must be non-zero)\n");
+		return -EINVAL;
+	}
+
+	if (cs == NULL) {
+		cs = kzalloc(sizeof(*cs), GFP_KERNEL);
+		if (!cs)
+			return -ENOMEM;
+		spi->controller_state = cs;
+	}
+
+	/*
+	 * We set all bits of the SPI0_MODE register, so,
+	 * no need to read-modify-write
+	 */
+	cs->mode = SPI_PPC4XX_MODE_SPE;
+
+	switch (spi->mode & SPI_MODE_X_MASK) {
+	case SPI_MODE_0:
+		cs->mode |= SPI_CLK_MODE0;
+		break;
+	case SPI_MODE_1:
+		cs->mode |= SPI_CLK_MODE1;
+		break;
+	case SPI_MODE_2:
+		cs->mode |= SPI_CLK_MODE2;
+		break;
+	case SPI_MODE_3:
+		cs->mode |= SPI_CLK_MODE3;
+		break;
+	}
+
+	if (spi->mode & SPI_LSB_FIRST)
+		cs->mode |= SPI_PPC4XX_MODE_RD;
+
+	return 0;
+}
+
+static irqreturn_t spi_ppc4xx_int(int irq, void *dev_id)
+{
+	struct ppc4xx_spi *hw;
+	u8 status;
+	u8 data;
+	unsigned int count;
+
+	hw = (struct ppc4xx_spi *)dev_id;
+
+	status = in_8(&hw->regs->sr);
+	if (!status)
+		return IRQ_NONE;
+
+	/*
+	 * BSY de-asserts one cycle after the transfer is complete.  The
+	 * interrupt is asserted after the transfer is complete.  The exact
+	 * relationship is not documented, hence this code.
+	 */
+
+	if (unlikely(status & SPI_PPC4XX_SR_BSY)) {
+		u8 lstatus;
+		int cnt = 0;
+
+		dev_dbg(hw->dev, "got interrupt but spi still busy?\n");
+		do {
+			ndelay(10);
+			lstatus = in_8(&hw->regs->sr);
+		} while (++cnt < 100 && lstatus & SPI_PPC4XX_SR_BSY);
+
+		if (cnt >= 100) {
+			dev_err(hw->dev, "busywait: too many loops!\n");
+			complete(&hw->done);
+			return IRQ_HANDLED;
+		} else {
+			/* status is always 1 (RBR) here */
+			status = in_8(&hw->regs->sr);
+			dev_dbg(hw->dev, "loops %d status %x\n", cnt, status);
+		}
+	}
+
+	count = hw->count;
+	hw->count++;
+
+	/* RBR triggered this interrupt.  Therefore, data must be ready. */
+	data = in_8(&hw->regs->rxd);
+	if (hw->rx)
+		hw->rx[count] = data;
+
+	count++;
+
+	if (count < hw->len) {
+		data = hw->tx ? hw->tx[count] : 0;
+		out_8(&hw->regs->txd, data);
+		out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
+	} else {
+		complete(&hw->done);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void spi_ppc4xx_cleanup(struct spi_device *spi)
+{
+	kfree(spi->controller_state);
+}
+
+static void spi_ppc4xx_enable(struct ppc4xx_spi *hw)
+{
+	/*
+	 * On all 4xx PPC's the SPI bus is shared/multiplexed with
+	 * the 2nd I2C bus. We need to enable the SPI bus before
+	 * using it.
+	 */
+
+	/* need to clear bit 14 to enable SPC */
+	dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0);
+}
+
+/*
+ * platform_device layer stuff...
+ */
+static int spi_ppc4xx_of_probe(struct platform_device *op)
+{
+	struct ppc4xx_spi *hw;
+	struct spi_master *master;
+	struct spi_bitbang *bbp;
+	struct resource resource;
+	struct device_node *np = op->dev.of_node;
+	struct device *dev = &op->dev;
+	struct device_node *opbnp;
+	int ret;
+	const unsigned int *clk;
+
+	master = spi_alloc_master(dev, sizeof(*hw));
+	if (master == NULL)
+		return -ENOMEM;
+	master->dev.of_node = np;
+	platform_set_drvdata(op, master);
+	hw = spi_master_get_devdata(master);
+	hw->master = master;
+	hw->dev = dev;
+
+	init_completion(&hw->done);
+
+	/* Setup the state for the bitbang driver */
+	bbp = &hw->bitbang;
+	bbp->master = hw->master;
+	bbp->setup_transfer = spi_ppc4xx_setupxfer;
+	bbp->txrx_bufs = spi_ppc4xx_txrx;
+	bbp->use_dma = 0;
+	bbp->master->setup = spi_ppc4xx_setup;
+	bbp->master->cleanup = spi_ppc4xx_cleanup;
+	bbp->master->bits_per_word_mask = SPI_BPW_MASK(8);
+	bbp->master->use_gpio_descriptors = true;
+	/*
+	 * The SPI core will count the number of GPIO descriptors to figure
+	 * out the number of chip selects available on the platform.
+	 */
+	bbp->master->num_chipselect = 0;
+
+	/* the spi->mode bits understood by this driver: */
+	bbp->master->mode_bits =
+		SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST;
+
+	/* Get the clock for the OPB */
+	opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb");
+	if (opbnp == NULL) {
+		dev_err(dev, "OPB: cannot find node\n");
+		ret = -ENODEV;
+		goto free_master;
+	}
+	/* Get the clock (Hz) for the OPB */
+	clk = of_get_property(opbnp, "clock-frequency", NULL);
+	if (clk == NULL) {
+		dev_err(dev, "OPB: no clock-frequency property set\n");
+		of_node_put(opbnp);
+		ret = -ENODEV;
+		goto free_master;
+	}
+	hw->opb_freq = *clk;
+	hw->opb_freq >>= 2;
+	of_node_put(opbnp);
+
+	ret = of_address_to_resource(np, 0, &resource);
+	if (ret) {
+		dev_err(dev, "error while parsing device node resource\n");
+		goto free_master;
+	}
+	hw->mapbase = resource.start;
+	hw->mapsize = resource_size(&resource);
+
+	/* Sanity check */
+	if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) {
+		dev_err(dev, "too small to map registers\n");
+		ret = -EINVAL;
+		goto free_master;
+	}
+
+	/* Request IRQ */
+	hw->irqnum = irq_of_parse_and_map(np, 0);
+	ret = request_irq(hw->irqnum, spi_ppc4xx_int,
+			  0, "spi_ppc4xx_of", (void *)hw);
+	if (ret) {
+		dev_err(dev, "unable to allocate interrupt\n");
+		goto free_master;
+	}
+
+	if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) {
+		dev_err(dev, "resource unavailable\n");
+		ret = -EBUSY;
+		goto request_mem_error;
+	}
+
+	hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs));
+
+	if (!hw->regs) {
+		dev_err(dev, "unable to memory map registers\n");
+		ret = -ENXIO;
+		goto map_io_error;
+	}
+
+	spi_ppc4xx_enable(hw);
+
+	/* Finally register our spi controller */
+	dev->dma_mask = 0;
+	ret = spi_bitbang_start(bbp);
+	if (ret) {
+		dev_err(dev, "failed to register SPI master\n");
+		goto unmap_regs;
+	}
+
+	dev_info(dev, "driver initialized\n");
+
+	return 0;
+
+unmap_regs:
+	iounmap(hw->regs);
+map_io_error:
+	release_mem_region(hw->mapbase, hw->mapsize);
+request_mem_error:
+	free_irq(hw->irqnum, hw);
+free_master:
+	spi_master_put(master);
+
+	dev_err(dev, "initialization failed\n");
+	return ret;
+}
+
+static int spi_ppc4xx_of_remove(struct platform_device *op)
+{
+	struct spi_master *master = platform_get_drvdata(op);
+	struct ppc4xx_spi *hw = spi_master_get_devdata(master);
+
+	spi_bitbang_stop(&hw->bitbang);
+	release_mem_region(hw->mapbase, hw->mapsize);
+	free_irq(hw->irqnum, hw);
+	iounmap(hw->regs);
+	spi_master_put(master);
+	return 0;
+}
+
+static const struct of_device_id spi_ppc4xx_of_match[] = {
+	{ .compatible = "ibm,ppc4xx-spi", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match);
+
+static struct platform_driver spi_ppc4xx_of_driver = {
+	.probe = spi_ppc4xx_of_probe,
+	.remove = spi_ppc4xx_of_remove,
+	.driver = {
+		.name = DRIVER_NAME,
+		.of_match_table = spi_ppc4xx_of_match,
+	},
+};
+module_platform_driver(spi_ppc4xx_of_driver);
+
+MODULE_AUTHOR("Gary Jennejohn & Stefan Roese");
+MODULE_DESCRIPTION("Simple PPC4xx SPI Driver");
+MODULE_LICENSE("GPL");