sandbox: spi: Add SPI emulation bus

This adds a SPI framework for people to hook up simulated SPI clients.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/include/asm/config.h

@@ -9,4 +9,12 @@
 
 #define CONFIG_SANDBOX_ARCH
 
+/* Used by drivers/spi/sandbox_spi.c and arch/sandbox/include/asm/state.h */
+#ifndef CONFIG_SANDBOX_SPI_MAX_BUS
+#define CONFIG_SANDBOX_SPI_MAX_BUS 1
+#endif
+#ifndef CONFIG_SANDBOX_SPI_MAX_CS
+#define CONFIG_SANDBOX_SPI_MAX_CS 10
+#endif
+
 #endif

arch/sandbox/include/asm/spi.h

@@ -0,0 +1,58 @@
+/*
+ * Simulate a SPI port and clients (see README.sandbox for details)
+ *
+ * Copyright (c) 2011-2013 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef __ASM_SPI_H__
+#define __ASM_SPI_H__
+
+#include <linux/types.h>
+
+/*
+ * The interface between the SPI bus and the SPI client.  The bus will
+ * instantiate a client, and that then call into it via these entry
+ * points.  These should be enough for the client to emulate the SPI
+ * device just like the real hardware.
+ */
+struct sandbox_spi_emu_ops {
+	/* The bus wants to instantiate a new client, so setup everything */
+	int (*setup)(void **priv, const char *spec);
+	/* The bus is done with us, so break things down */
+	void (*free)(void *priv);
+	/* The CS has been "activated" -- we won't worry about low/high */
+	void (*cs_activate)(void *priv);
+	/* The CS has been "deactivated" -- we won't worry about low/high */
+	void (*cs_deactivate)(void *priv);
+	/* The client is rx-ing bytes from the bus, so it should tx some */
+	int (*xfer)(void *priv, const u8 *rx, u8 *tx, uint bytes);
+};
+
+/*
+ * There are times when the data lines are allowed to tristate.  What
+ * is actually sensed on the line depends on the hardware.  It could
+ * always be 0xFF/0x00 (if there are pull ups/downs), or things could
+ * float and so we'd get garbage back.  This func encapsulates that
+ * scenario so we can worry about the details here.
+ */
+static inline void sandbox_spi_tristate(u8 *buf, uint len)
+{
+	/* XXX: make this into a user config option ? */
+	memset(buf, 0xff, len);
+}
+
+/*
+ * Extract the bus/cs from the spi spec and return the start of the spi
+ * client spec.  If the bus/cs are invalid for the current config, then
+ * it returns NULL.
+ *
+ * Example: arg="0:1:foo" will set bus to 0, cs to 1, and return "foo"
+ */
+const char *sandbox_spi_parse_spec(const char *arg, unsigned long *bus,
+				   unsigned long *cs);
+
+#endif

arch/sandbox/include/asm/state.h

@@ -15,6 +15,11 @@ enum exit_type_id {
 	STATE_EXIT_POWER_OFF,
 };
 
+struct sandbox_spi_info {
+	const char *spec;
+	const struct sandbox_spi_emu_ops *ops;
+};
+
 /* The complete state of the test system */
 struct sandbox_state {
 	const char *cmd;		/* Command to execute */
@@ -23,6 +28,10 @@ struct sandbox_state {
 	const char *parse_err;		/* Error to report from parsing */
 	int argc;			/* Program arguments */
 	char **argv;
+
+	/* Pointer to information for each SPI bus/cs */
+	struct sandbox_spi_info spi[CONFIG_SANDBOX_SPI_MAX_BUS]
+					[CONFIG_SANDBOX_SPI_MAX_CS];
 };
 
 /**

drivers/spi/Makefile

@@ -27,6 +27,7 @@ obj-$(CONFIG_MXC_SPI) += mxc_spi.o
 obj-$(CONFIG_MXS_SPI) += mxs_spi.o
 obj-$(CONFIG_OC_TINY_SPI) += oc_tiny_spi.o
 obj-$(CONFIG_OMAP3_SPI) += omap3_spi.o
+obj-$(CONFIG_SANDBOX_SPI) += sandbox_spi.o
 obj-$(CONFIG_SOFT_SPI) += soft_spi.o
 obj-$(CONFIG_SH_SPI) += sh_spi.o
 obj-$(CONFIG_FSL_ESPI) += fsl_espi.o

drivers/spi/sandbox_spi.c

@@ -0,0 +1,204 @@
+/*
+ * Simulate a SPI port
+ *
+ * Copyright (c) 2011-2013 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <spi.h>
+#include <os.h>
+
+#include <asm/errno.h>
+#include <asm/spi.h>
+#include <asm/state.h>
+
+#ifndef CONFIG_SPI_IDLE_VAL
+# define CONFIG_SPI_IDLE_VAL 0xFF
+#endif
+
+struct sandbox_spi_slave {
+	struct spi_slave slave;
+	const struct sandbox_spi_emu_ops *ops;
+	void *priv;
+};
+
+#define to_sandbox_spi_slave(s) container_of(s, struct sandbox_spi_slave, slave)
+
+const char *sandbox_spi_parse_spec(const char *arg, unsigned long *bus,
+				   unsigned long *cs)
+{
+	char *endp;
+
+	*bus = simple_strtoul(arg, &endp, 0);
+	if (*endp != ':' || *bus >= CONFIG_SANDBOX_SPI_MAX_BUS)
+		return NULL;
+
+	*cs = simple_strtoul(endp + 1, &endp, 0);
+	if (*endp != ':' || *cs >= CONFIG_SANDBOX_SPI_MAX_CS)
+		return NULL;
+
+	return endp + 1;
+}
+
+int spi_cs_is_valid(unsigned int bus, unsigned int cs)
+{
+	return bus < CONFIG_SANDBOX_SPI_MAX_BUS &&
+		cs < CONFIG_SANDBOX_SPI_MAX_CS;
+}
+
+void spi_cs_activate(struct spi_slave *slave)
+{
+	struct sandbox_spi_slave *sss = to_sandbox_spi_slave(slave);
+
+	debug("sandbox_spi: activating CS\n");
+	if (sss->ops->cs_activate)
+		sss->ops->cs_activate(sss->priv);
+}
+
+void spi_cs_deactivate(struct spi_slave *slave)
+{
+	struct sandbox_spi_slave *sss = to_sandbox_spi_slave(slave);
+
+	debug("sandbox_spi: deactivating CS\n");
+	if (sss->ops->cs_deactivate)
+		sss->ops->cs_deactivate(sss->priv);
+}
+
+void spi_init(void)
+{
+}
+
+void spi_set_speed(struct spi_slave *slave, uint hz)
+{
+}
+
+struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
+		unsigned int max_hz, unsigned int mode)
+{
+	struct sandbox_spi_slave *sss;
+	struct sandbox_state *state = state_get_current();
+	const char *spec;
+
+	if (!spi_cs_is_valid(bus, cs)) {
+		debug("sandbox_spi: Invalid SPI bus/cs\n");
+		return NULL;
+	}
+
+	sss = spi_alloc_slave(struct sandbox_spi_slave, bus, cs);
+	if (!sss) {
+		debug("sandbox_spi: Out of memory\n");
+		return NULL;
+	}
+
+	spec = state->spi[bus][cs].spec;
+	sss->ops = state->spi[bus][cs].ops;
+	if (!spec || !sss->ops || sss->ops->setup(&sss->priv, spec)) {
+		free(sss);
+		printf("sandbox_spi: unable to locate a slave client\n");
+		return NULL;
+	}
+
+	return &sss->slave;
+}
+
+void spi_free_slave(struct spi_slave *slave)
+{
+	struct sandbox_spi_slave *sss = to_sandbox_spi_slave(slave);
+
+	debug("sandbox_spi: releasing slave\n");
+
+	if (sss->ops->free)
+		sss->ops->free(sss->priv);
+
+	free(sss);
+}
+
+static int spi_bus_claim_cnt[CONFIG_SANDBOX_SPI_MAX_BUS];
+
+int spi_claim_bus(struct spi_slave *slave)
+{
+	if (spi_bus_claim_cnt[slave->bus]++) {
+		printf("sandbox_spi: error: bus already claimed: %d!\n",
+		       spi_bus_claim_cnt[slave->bus]);
+	}
+
+	return 0;
+}
+
+void spi_release_bus(struct spi_slave *slave)
+{
+	if (--spi_bus_claim_cnt[slave->bus]) {
+		printf("sandbox_spi: error: bus freed too often: %d!\n",
+		       spi_bus_claim_cnt[slave->bus]);
+	}
+}
+
+int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
+		void *din, unsigned long flags)
+{
+	struct sandbox_spi_slave *sss = to_sandbox_spi_slave(slave);
+	uint bytes = bitlen / 8, i;
+	int ret = 0;
+	u8 *tx = (void *)dout, *rx = din;
+
+	if (bitlen == 0)
+		goto done;
+
+	/* we can only do 8 bit transfers */
+	if (bitlen % 8) {
+		printf("sandbox_spi: xfer: invalid bitlen size %u; needs to be 8bit\n",
+		       bitlen);
+		flags |= SPI_XFER_END;
+		goto done;
+	}
+
+	if (flags & SPI_XFER_BEGIN)
+		spi_cs_activate(slave);
+
+	/* make sure rx/tx buffers are full so clients can assume */
+	if (!tx) {
+		debug("sandbox_spi: xfer: auto-allocating tx scratch buffer\n");
+		tx = malloc(bytes);
+		if (!tx) {
+			debug("sandbox_spi: Out of memory\n");
+			return -ENOMEM;
+		}
+	}
+	if (!rx) {
+		debug("sandbox_spi: xfer: auto-allocating rx scratch buffer\n");
+		rx = malloc(bytes);
+		if (!rx) {
+			debug("sandbox_spi: Out of memory\n");
+			return -ENOMEM;
+		}
+	}
+
+	debug("sandbox_spi: xfer: bytes = %u\n tx:", bytes);
+	for (i = 0; i < bytes; ++i)
+		debug(" %u:%02x", i, tx[i]);
+	debug("\n");
+
+	ret = sss->ops->xfer(sss->priv, tx, rx, bytes);
+
+	debug("sandbox_spi: xfer: got back %i (that's %s)\n rx:",
+	      ret, ret ? "bad" : "good");
+	for (i = 0; i < bytes; ++i)
+		debug(" %u:%02x", i, rx[i]);
+	debug("\n");
+
+	if (tx != dout)
+		free(tx);
+	if (rx != din)
+		free(rx);
+
+ done:
+	if (flags & SPI_XFER_END)
+		spi_cs_deactivate(slave);
+
+	return ret;
+}