cros: add I2C support for cros_ec

This patch adds I2C support for carrying out the cros_ec protocol.

Signed-off-by: Randall Spangler <rspangler@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Hung-ying Tyan <tyanh@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

drivers/misc/Makefile

@@ -29,6 +29,7 @@ COBJS-$(CONFIG_ALI152X) += ali512x.o
 COBJS-$(CONFIG_DS4510)  += ds4510.o
 COBJS-$(CONFIG_CBMEM_CONSOLE) += cbmem_console.o
 COBJS-$(CONFIG_CROS_EC) += cros_ec.o
+COBJS-$(CONFIG_CROS_EC_I2C) += cros_ec_i2c.o
 COBJS-$(CONFIG_FSL_IIM) += fsl_iim.o
 COBJS-$(CONFIG_GPIO_LED) += gpio_led.o
 COBJS-$(CONFIG_FSL_MC9SDZ60) += mc9sdz60.o

drivers/misc/cros_ec_i2c.c

@@ -0,0 +1,199 @@
+/*
+ * Chromium OS cros_ec driver - I2C interface
+ *
+ * Copyright (c) 2012 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * The Matrix Keyboard Protocol driver handles talking to the keyboard
+ * controller chip. Mostly this is for keyboard functions, but some other
+ * things have slipped in, so we provide generic services to talk to the
+ * KBC.
+ */
+
+#include <common.h>
+#include <i2c.h>
+#include <cros_ec.h>
+
+#ifdef DEBUG_TRACE
+#define debug_trace(fmt, b...)	debug(fmt, #b)
+#else
+#define debug_trace(fmt, b...)
+#endif
+
+int cros_ec_i2c_command(struct cros_ec_dev *dev, uint8_t cmd, int cmd_version,
+		     const uint8_t *dout, int dout_len,
+		     uint8_t **dinp, int din_len)
+{
+	int old_bus = 0;
+	/* version8, cmd8, arglen8, out8[dout_len], csum8 */
+	int out_bytes = dout_len + 4;
+	/* response8, arglen8, in8[din_len], checksum8 */
+	int in_bytes = din_len + 3;
+	uint8_t *ptr;
+	/* Receive input data, so that args will be dword aligned */
+	uint8_t *in_ptr;
+	int ret;
+
+	old_bus = i2c_get_bus_num();
+
+	/*
+	 * Sanity-check I/O sizes given transaction overhead in internal
+	 * buffers.
+	 */
+	if (out_bytes > sizeof(dev->dout)) {
+		debug("%s: Cannot send %d bytes\n", __func__, dout_len);
+		return -1;
+	}
+	if (in_bytes > sizeof(dev->din)) {
+		debug("%s: Cannot receive %d bytes\n", __func__, din_len);
+		return -1;
+	}
+	assert(dout_len >= 0);
+	assert(dinp);
+
+	/*
+	 * Copy command and data into output buffer so we can do a single I2C
+	 * burst transaction.
+	 */
+	ptr = dev->dout;
+
+	/*
+	 * in_ptr starts of pointing to a dword-aligned input data buffer.
+	 * We decrement it back by the number of header bytes we expect to
+	 * receive, so that the first parameter of the resulting input data
+	 * will be dword aligned.
+	 */
+	in_ptr = dev->din + sizeof(int64_t);
+	if (!dev->cmd_version_is_supported) {
+		/* Send an old-style command */
+		*ptr++ = cmd;
+		out_bytes = dout_len + 1;
+		in_bytes = din_len + 2;
+		in_ptr--;	/* Expect just a status byte */
+	} else {
+		*ptr++ = EC_CMD_VERSION0 + cmd_version;
+		*ptr++ = cmd;
+		*ptr++ = dout_len;
+		in_ptr -= 2;	/* Expect status, length bytes */
+	}
+	memcpy(ptr, dout, dout_len);
+	ptr += dout_len;
+
+	if (dev->cmd_version_is_supported)
+		*ptr++ = (uint8_t)
+			 cros_ec_calc_checksum(dev->dout, dout_len + 3);
+
+	/* Set to the proper i2c bus */
+	if (i2c_set_bus_num(dev->bus_num)) {
+		debug("%s: Cannot change to I2C bus %d\n", __func__,
+			dev->bus_num);
+		return -1;
+	}
+
+	/* Send output data */
+	cros_ec_dump_data("out", -1, dev->dout, out_bytes);
+	ret = i2c_write(dev->addr, 0, 0, dev->dout, out_bytes);
+	if (ret) {
+		debug("%s: Cannot complete I2C write to 0x%x\n",
+			__func__, dev->addr);
+		ret = -1;
+	}
+
+	if (!ret) {
+		ret = i2c_read(dev->addr, 0, 0, in_ptr, in_bytes);
+		if (ret) {
+			debug("%s: Cannot complete I2C read from 0x%x\n",
+				__func__, dev->addr);
+			ret = -1;
+		}
+	}
+
+	/* Return to original bus number */
+	i2c_set_bus_num(old_bus);
+	if (ret)
+		return ret;
+
+	if (*in_ptr != EC_RES_SUCCESS) {
+		debug("%s: Received bad result code %d\n", __func__, *in_ptr);
+		return -(int)*in_ptr;
+	}
+
+	if (dev->cmd_version_is_supported) {
+		int len, csum;
+
+		len = in_ptr[1];
+		if (len + 3 > sizeof(dev->din)) {
+			debug("%s: Received length %#02x too large\n",
+			      __func__, len);
+			return -1;
+		}
+		csum = cros_ec_calc_checksum(in_ptr, 2 + len);
+		if (csum != in_ptr[2 + len]) {
+			debug("%s: Invalid checksum rx %#02x, calced %#02x\n",
+			      __func__, in_ptr[2 + din_len], csum);
+			return -1;
+		}
+		din_len = min(din_len, len);
+		cros_ec_dump_data("in", -1, in_ptr, din_len + 3);
+	} else {
+		cros_ec_dump_data("in (old)", -1, in_ptr, in_bytes);
+	}
+
+	/* Return pointer to dword-aligned input data, if any */
+	*dinp = dev->din + sizeof(int64_t);
+
+	return din_len;
+}
+
+int cros_ec_i2c_decode_fdt(struct cros_ec_dev *dev, const void *blob)
+{
+	/* Decode interface-specific FDT params */
+	dev->max_frequency = fdtdec_get_int(blob, dev->node,
+					    "i2c-max-frequency", 100000);
+	dev->bus_num = i2c_get_bus_num_fdt(dev->parent_node);
+	if (dev->bus_num == -1) {
+		debug("%s: Failed to read bus number\n", __func__);
+		return -1;
+	}
+	dev->addr = fdtdec_get_int(blob, dev->node, "reg", -1);
+	if (dev->addr == -1) {
+		debug("%s: Failed to read device address\n", __func__);
+		return -1;
+	}
+
+	return 0;
+}
+
+/**
+ * Initialize I2C protocol.
+ *
+ * @param dev		CROS_EC device
+ * @param blob		Device tree blob
+ * @return 0 if ok, -1 on error
+ */
+int cros_ec_i2c_init(struct cros_ec_dev *dev, const void *blob)
+{
+	i2c_init(dev->max_frequency, dev->addr);
+
+	dev->cmd_version_is_supported = 0;
+
+	return 0;
+}