cros: exynos: add SPI support for cros_ec

[karo-tx-uboot.git] / drivers / misc / cros_ec_spi.c

diff --git a/drivers/misc/cros_ec_spi.c b/drivers/misc/cros_ec_spi.c
new file mode 100644 (file)
index 0000000..e15c833
--- /dev/null
+++ b/drivers/misc/cros_ec_spi.c
@@ -0,0 +1,161 @@
+/*
+ * Chromium OS cros_ec driver - SPI 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 <cros_ec.h>
+#include <spi.h>
+
+/**
+ * Send a command to a LPC CROS_EC device and return the reply.
+ *
+ * The device's internal input/output buffers are used.
+ *
+ * @param dev          CROS_EC device
+ * @param cmd          Command to send (EC_CMD_...)
+ * @param cmd_version  Version of command to send (EC_VER_...)
+ * @param dout         Output data (may be NULL If dout_len=0)
+ * @param dout_len      Size of output data in bytes
+ * @param dinp         Returns pointer to response data. This will be
+ *                     untouched unless we return a value > 0.
+ * @param din_len      Maximum size of response in bytes
+ * @return number of bytes in response, or -1 on error
+ */
+int cros_ec_spi_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 in_bytes = din_len + 4;     /* status, length, checksum, trailer */
+       uint8_t *out;
+       uint8_t *p;
+       int csum, len;
+       int rv;
+
+       /*
+        * Sanity-check input size to make sure it plus transaction overhead
+        * fits in the internal device buffer.
+        */
+       if (in_bytes > sizeof(dev->din)) {
+               debug("%s: Cannot receive %d bytes\n", __func__, din_len);
+               return -1;
+       }
+
+       /* We represent message length as a byte */
+       if (dout_len > 0xff) {
+               debug("%s: Cannot send %d bytes\n", __func__, dout_len);
+               return -1;
+       }
+
+       /*
+        * Clear input buffer so we don't get false hits for MSG_HEADER
+        */
+       memset(dev->din, '\0', in_bytes);
+
+       if (spi_claim_bus(dev->spi)) {
+               debug("%s: Cannot claim SPI bus\n", __func__);
+               return -1;
+       }
+
+       out = dev->dout;
+       out[0] = cmd_version;
+       out[1] = cmd;
+       out[2] = (uint8_t)dout_len;
+       memcpy(out + 3, dout, dout_len);
+       csum = cros_ec_calc_checksum(out, 3)
+              + cros_ec_calc_checksum(dout, dout_len);
+       out[3 + dout_len] = (uint8_t)csum;
+
+       /*
+        * Send output data and receive input data starting such that the
+        * message body will be dword aligned.
+        */
+       p = dev->din + sizeof(int64_t) - 2;
+       len = dout_len + 4;
+       cros_ec_dump_data("out", cmd, out, len);
+       rv = spi_xfer(dev->spi, max(len, in_bytes) * 8, out, p,
+                     SPI_XFER_BEGIN | SPI_XFER_END);
+
+       spi_release_bus(dev->spi);
+
+       if (rv) {
+               debug("%s: Cannot complete SPI transfer\n", __func__);
+               return -1;
+       }
+
+       len = min(p[1], din_len);
+       cros_ec_dump_data("in", -1, p, len + 3);
+
+       /* Response code is first byte of message */
+       if (p[0] != EC_RES_SUCCESS) {
+               printf("%s: Returned status %d\n", __func__, p[0]);
+               return -(int)(p[0]);
+       }
+
+       /* Check checksum */
+       csum = cros_ec_calc_checksum(p, len + 2);
+       if (csum != p[len + 2]) {
+               debug("%s: Invalid checksum rx %#02x, calced %#02x\n", __func__,
+                     p[2 + len], csum);
+               return -1;
+       }
+
+       /* Anything else is the response data */
+       *dinp = p + 2;
+
+       return len;
+}
+
+int cros_ec_spi_decode_fdt(struct cros_ec_dev *dev, const void *blob)
+{
+       /* Decode interface-specific FDT params */
+       dev->max_frequency = fdtdec_get_int(blob, dev->node,
+                                           "spi-max-frequency", 500000);
+       dev->cs = fdtdec_get_int(blob, dev->node, "reg", 0);
+
+       return 0;
+}
+
+/**
+ * Initialize SPI protocol.
+ *
+ * @param dev          CROS_EC device
+ * @param blob         Device tree blob
+ * @return 0 if ok, -1 on error
+ */
+int cros_ec_spi_init(struct cros_ec_dev *dev, const void *blob)
+{
+       dev->spi = spi_setup_slave_fdt(blob, dev->parent_node,
+                                      dev->cs, dev->max_frequency, 0);
+       if (!dev->spi) {
+               debug("%s: Could not setup SPI slave\n", __func__);
+               return -1;
+       }
+
+       return 0;
+}