spi: microblaze: Adds driver for Xilinx SPI controller

This is an improved version of the driver patch original
submitted by Graeme Smecher <graeme.smecher@mail.mcgill.ca>

The changes are:
    - remove hard coded Xilinx BSP defines (XPAR_SPI_*) and
      use CONFIG_SYS_SPI_BASE from config.h instead
    - add extensive register struct definitions
    - remove offset calculation for register access and
      use the new register struct instead
    - move default SPI controller configuration from
      spi_setup_slave() to spi_claim_bus()
    - add spi_set_speed()
    - insert SPI controller deactivation in spi_release_bus()
    - protect while loops in spi_xfer() with counter / timeouts
    - support SPI mode flags: LSB_FIRST, CPHA, CPOL, LOOP

Come from:
    http://patchwork.ozlabs.org/patch/71797/

Signed-off-by: Stephan Linz <linz@li-pro.net>
Tested-by: Michal Simek <monstr@monstr.eu>

1 files changed, 214 insertions, 0 deletions

diff --git a/drivers/spi/xilinx_spi.c b/drivers/spi/xilinx_spi.c
new file mode 100644
index 0000000..e563c19
--- /dev/null
+++ b/drivers/spi/xilinx_spi.c
@@ -0,0 +1,214 @@
+/*
+ * Xilinx SPI driver
+ *
+ * supports 8 bit SPI transfers only, with or w/o FIFO
+ *
+ * based on bfin_spi.c, by way of altera_spi.c
+ * Copyright (c) 2005-2008 Analog Devices Inc.
+ * Copyright (c) 2010 Thomas Chou <thomas@wytron.com.tw>
+ * Copyright (c) 2010 Graeme Smecher <graeme.smecher@mail.mcgill.ca>
+ * Copyright (c) 2012 Stephan Linz <linz@li-pro.net>
+ *
+ * Licensed under the GPL-2 or later.
+ *
+ * [0]: http://www.xilinx.com/support/documentation
+ *
+ * [S]:	[0]/ip_documentation/xps_spi.pdf
+ *	[0]/ip_documentation/axi_spi_ds742.pdf
+ */
+#include <config.h>
+#include <common.h>
+#include <malloc.h>
+#include <spi.h>
+
+#include "xilinx_spi.h"
+
+#ifndef CONFIG_SYS_XILINX_SPI_LIST
+#define CONFIG_SYS_XILINX_SPI_LIST	{ CONFIG_SYS_SPI_BASE }
+#endif
+
+#ifndef CONFIG_XILINX_SPI_IDLE_VAL
+#define CONFIG_XILINX_SPI_IDLE_VAL	0xff
+#endif
+
+#define XILSPI_SPICR_DFLT_ON		(SPICR_MANUAL_SS | \
+					 SPICR_MASTER_MODE | \
+					 SPICR_SPE)
+
+#define XILSPI_SPICR_DFLT_OFF		(SPICR_MASTER_INHIBIT | \
+					 SPICR_MANUAL_SS)
+
+#define XILSPI_MAX_XFER_BITS		8
+
+static unsigned long xilinx_spi_base_list[] = CONFIG_SYS_XILINX_SPI_LIST;
+
+__attribute__((weak))
+int spi_cs_is_valid(unsigned int bus, unsigned int cs)
+{
+	return bus < ARRAY_SIZE(xilinx_spi_base_list) && cs < 32;
+}
+
+__attribute__((weak))
+void spi_cs_activate(struct spi_slave *slave)
+{
+	struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
+
+	writel(SPISSR_ACT(slave->cs), &xilspi->regs->spissr);
+}
+
+__attribute__((weak))
+void spi_cs_deactivate(struct spi_slave *slave)
+{
+	struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
+
+	writel(SPISSR_OFF, &xilspi->regs->spissr);
+}
+
+void spi_init(void)
+{
+	/* do nothing */
+}
+
+void spi_set_speed(struct spi_slave *slave, uint hz)
+{
+	/* xilinx spi core does not support programmable speed */
+}
+
+struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
+				  unsigned int max_hz, unsigned int mode)
+{
+	struct xilinx_spi_slave *xilspi;
+	struct xilinx_spi_reg *regs;
+
+	if (!spi_cs_is_valid(bus, cs)) {
+		printf("XILSPI error: %s: unsupported bus %d / cs %d\n",
+				__func__, bus, cs);
+		return NULL;
+	}
+
+	xilspi = malloc(sizeof(*xilspi));
+	if (!xilspi) {
+		printf("XILSPI error: %s: malloc of SPI structure failed\n",
+				__func__);
+		return NULL;
+	}
+	xilspi->slave.bus = bus;
+	xilspi->slave.cs = cs;
+	xilspi->regs = (struct xilinx_spi_reg *)xilinx_spi_base_list[bus];
+	xilspi->freq = max_hz;
+	xilspi->mode = mode;
+	debug("%s: bus:%i cs:%i base:%p mode:%x max_hz:%d\n", __func__,
+		bus, cs, xilspi->regs, xilspi->mode, xilspi->freq);
+
+	return &xilspi->slave;
+}
+
+void spi_free_slave(struct spi_slave *slave)
+{
+	struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
+
+	free(xilspi);
+}
+
+int spi_claim_bus(struct spi_slave *slave)
+{
+	struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
+	u32 spicr;
+
+	debug("%s: bus:%i cs:%i\n", __func__, slave->bus, slave->cs);
+	writel(SPISSR_OFF, &xilspi->regs->spissr);
+
+	spicr = XILSPI_SPICR_DFLT_ON;
+	if (xilspi->mode & SPI_LSB_FIRST)
+		spicr |= SPICR_LSB_FIRST;
+	if (xilspi->mode & SPI_CPHA)
+		spicr |= SPICR_CPHA;
+	if (xilspi->mode & SPI_CPOL)
+		spicr |= SPICR_CPOL;
+	if (xilspi->mode & SPI_LOOP)
+		spicr |= SPICR_LOOP;
+
+	writel(spicr, &xilspi->regs->spicr);
+	return 0;
+}
+
+void spi_release_bus(struct spi_slave *slave)
+{
+	struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
+
+	debug("%s: bus:%i cs:%i\n", __func__, slave->bus, slave->cs);
+	writel(SPISSR_OFF, &xilspi->regs->spissr);
+	writel(XILSPI_SPICR_DFLT_OFF, &xilspi->regs->spicr);
+}
+
+int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
+	     void *din, unsigned long flags)
+{
+	struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
+	/* assume spi core configured to do 8 bit transfers */
+	unsigned int bytes = bitlen / XILSPI_MAX_XFER_BITS;
+	const unsigned char *txp = dout;
+	unsigned char *rxp = din;
+	unsigned rxecount = 17;	/* max. 16 elements in FIFO, leftover 1 */
+
+	debug("%s: bus:%i cs:%i bitlen:%i bytes:%i flags:%lx\n", __func__,
+		slave->bus, slave->cs, bitlen, bytes, flags);
+	if (bitlen == 0)
+		goto done;
+
+	if (bitlen % XILSPI_MAX_XFER_BITS) {
+		printf("XILSPI warning: %s: Not a multiple of %d bits\n",
+				__func__, XILSPI_MAX_XFER_BITS);
+		flags |= SPI_XFER_END;
+		goto done;
+	}
+
+	/* empty read buffer */
+	while (rxecount && !(readl(&xilspi->regs->spisr) & SPISR_RX_EMPTY)) {
+		readl(&xilspi->regs->spidrr);
+		rxecount--;
+	}
+
+	if (!rxecount) {
+		printf("XILSPI error: %s: Rx buffer not empty\n", __func__);
+		return -1;
+	}
+
+	if (flags & SPI_XFER_BEGIN)
+		spi_cs_activate(slave);
+
+	while (bytes--) {
+		unsigned timeout = /* at least 1usec or greater, leftover 1 */
+			xilspi->freq > XILSPI_MAX_XFER_BITS * 1000000 ? 2 :
+			(XILSPI_MAX_XFER_BITS * 1000000 / xilspi->freq) + 1;
+
+		/* get Tx element from data out buffer and count up */
+		unsigned char d = txp ? *txp++ : CONFIG_XILINX_SPI_IDLE_VAL;
+		debug("%s: tx:%x ", __func__, d);
+
+		/* write out and wait for processing (receive data) */
+		writel(d & SPIDTR_8BIT_MASK, &xilspi->regs->spidtr);
+		while (timeout && readl(&xilspi->regs->spisr)
+						& SPISR_RX_EMPTY) {
+			timeout--;
+			udelay(1);
+		}
+
+		if (!timeout) {
+			printf("XILSPI error: %s: Xfer timeout\n", __func__);
+			return -1;
+		}
+
+		/* read Rx element and push into data in buffer */
+		d = readl(&xilspi->regs->spidrr) & SPIDRR_8BIT_MASK;
+		if (rxp)
+			*rxp++ = d;
+		debug("rx:%x\n", d);
+	}
+
+ done:
+	if (flags & SPI_XFER_END)
+		spi_cs_deactivate(slave);
+
+	return 0;
+}