Input: atmel_mxt_ts - calculate and check CRC in config file

By validating the checksum, we can identify if the configuration is
corrupt.  In addition, this patch writes the configuration in a short
series of block writes rather than as many individual values.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Acked-by: Yufeng Shen <miletus@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 177 insertions, 55 deletions

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index c6b5e7dbd942..d2feb9c771a4 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -48,6 +48,8 @@
 #define MXT_OBJECT_START        0x07
 
 #define MXT_OBJECT_SIZE         6
+#define MXT_INFO_CHECKSUM_SIZE  3
+#define MXT_MAX_BLOCK_WRITE     256
 
 /* Object types */
 #define MXT_DEBUG_DIAGNOSTIC_T37        37
@@ -238,12 +240,15 @@ struct mxt_data {
         unsigned int max_x;
         unsigned int max_y;
         bool in_bootloader;
+        u16 mem_size;
         u32 config_crc;
+        u32 info_crc;
         u8 bootloader_addr;
 
         /* Cached parameters from object table */
         u8 T6_reportid;
         u16 T6_address;
+        u16 T7_address;
         u8 T9_reportid_min;
         u8 T9_reportid_max;
         u8 T19_reportid;
@@ -849,6 +854,45 @@ static void mxt_update_crc(struct mxt_data *data, u8 cmd, u8 value)
         mxt_wait_for_completion(data, &data->crc_completion, MXT_CRC_TIMEOUT);
 }
 
+static void mxt_calc_crc24(u32 *crc, u8 firstbyte, u8 secondbyte)
+{
+        static const unsigned int crcpoly = 0x80001B;
+        u32 result;
+        u32 data_word;
+
+        data_word = (secondbyte << 8) | firstbyte;
+        result = ((*crc << 1) ^ data_word);
+
+        if (result & 0x1000000)
+                result ^= crcpoly;
+
+        *crc = result;
+}
+
+static u32 mxt_calculate_crc(u8 *base, off_t start_off, off_t end_off)
+{
+        u32 crc = 0;
+        u8 *ptr = base + start_off;
+        u8 *last_val = base + end_off - 1;
+
+        if (end_off < start_off)
+                return -EINVAL;
+
+        while (ptr < last_val) {
+                mxt_calc_crc24(&crc, *ptr, *(ptr + 1));
+                ptr += 2;
+        }
+
+        /* if len is odd, fill the last byte with 0 */
+        if (ptr == last_val)
+                mxt_calc_crc24(&crc, *ptr, 0);
+
+        /* Mask to 24-bit */
+        crc &= 0x00FFFFFF;
+
+        return crc;
+}
+
 /*
  * mxt_update_cfg - download configuration to chip
  *
@@ -875,9 +919,13 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *cfg)
         struct mxt_object *object;
         int ret;
         int offset;
-        int pos;
+        int data_pos;
+        int byte_offset;
         int i;
-        u32 info_crc, config_crc;
+        int cfg_start_ofs;
+        u32 info_crc, config_crc, calculated_crc;
+        u8 *config_mem;
+        size_t config_mem_size;
         unsigned int type, instance, size;
         u8 val;
         u16 reg;
@@ -890,11 +938,11 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *cfg)
                 goto release;
         }
 
-        pos = strlen(MXT_CFG_MAGIC);
+        data_pos = strlen(MXT_CFG_MAGIC);
 
         /* Load information block and check */
         for (i = 0; i < sizeof(struct mxt_info); i++) {
-                ret = sscanf(cfg->data + pos, "%hhx%n",
+                ret = sscanf(cfg->data + data_pos, "%hhx%n",
                              (unsigned char *)&cfg_info + i,
                              &offset);
                 if (ret != 1) {
@@ -903,7 +951,7 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *cfg)
                         goto release;
                 }
 
-                pos += offset;
+                data_pos += offset;
         }
 
         if (cfg_info.family_id != data->info.family_id) {
@@ -918,125 +966,188 @@ static int mxt_update_cfg(struct mxt_data *data, const struct firmware *cfg)
                 goto release;
         }
 
-        if (cfg_info.version != data->info.version)
-                dev_err(dev, "Warning: version mismatch!\n");
-
-        if (cfg_info.build != data->info.build)
-                dev_err(dev, "Warning: build num mismatch!\n");
-
-        ret = sscanf(cfg->data + pos, "%x%n", &info_crc, &offset);
+        /* Read CRCs */
+        ret = sscanf(cfg->data + data_pos, "%x%n", &info_crc, &offset);
         if (ret != 1) {
                 dev_err(dev, "Bad format: failed to parse Info CRC\n");
                 ret = -EINVAL;
                 goto release;
         }
-        pos += offset;
+        data_pos += offset;
 
-        /* Check config CRC */
-        ret = sscanf(cfg->data + pos, "%x%n", &config_crc, &offset);
+        ret = sscanf(cfg->data + data_pos, "%x%n", &config_crc, &offset);
         if (ret != 1) {
                 dev_err(dev, "Bad format: failed to parse Config CRC\n");
                 ret = -EINVAL;
                 goto release;
         }
-        pos += offset;
+        data_pos += offset;
 
-        if (data->config_crc == config_crc) {
-                dev_dbg(dev, "Config CRC 0x%06X: OK\n", config_crc);
-                ret = 0;
-                goto release;
+        /*
+         * The Info Block CRC is calculated over mxt_info and the object
+         * table. If it does not match then we are trying to load the
+         * configuration from a different chip or firmware version, so
+         * the configuration CRC is invalid anyway.
+         */
+        if (info_crc == data->info_crc) {
+                if (config_crc == 0 || data->config_crc == 0) {
+                        dev_info(dev, "CRC zero, attempting to apply config\n");
+                } else if (config_crc == data->config_crc) {
+                        dev_dbg(dev, "Config CRC 0x%06X: OK\n",
+                                 data->config_crc);
+                        ret = 0;
+                        goto release;
+                } else {
+                        dev_info(dev, "Config CRC 0x%06X: does not match file 0x%06X\n",
+                                 data->config_crc, config_crc);
+                }
+        } else {
+                dev_warn(dev,
+                         "Warning: Info CRC error - device=0x%06X file=0x%06X\n",
+                         data->info_crc, info_crc);
         }
 
-        dev_info(dev, "Config CRC 0x%06X: does not match file 0x%06X\n",
-                 data->config_crc, config_crc);
+        /* Malloc memory to store configuration */
+        cfg_start_ofs = MXT_OBJECT_START +
+                        data->info.object_num * sizeof(struct mxt_object) +
+                        MXT_INFO_CHECKSUM_SIZE;
+        config_mem_size = data->mem_size - cfg_start_ofs;
+        config_mem = kzalloc(config_mem_size, GFP_KERNEL);
+        if (!config_mem) {
+                dev_err(dev, "Failed to allocate memory\n");
+                ret = -ENOMEM;
+                goto release;
+        }
 
-        while (pos < cfg->size) {
+        while (data_pos < cfg->size) {
                 /* Read type, instance, length */
-                ret = sscanf(cfg->data + pos, "%x %x %x%n",
+                ret = sscanf(cfg->data + data_pos, "%x %x %x%n",
                              &type, &instance, &size, &offset);
                 if (ret == 0) {
                         /* EOF */
-                        ret = 1;
-                        goto release;
+                        break;
                 } else if (ret != 3) {
                         dev_err(dev, "Bad format: failed to parse object\n");
                         ret = -EINVAL;
-                        goto release;
+                        goto release_mem;
                 }
-                pos += offset;
+                data_pos += offset;
 
                 object = mxt_get_object(data, type);
                 if (!object) {
                         /* Skip object */
                         for (i = 0; i < size; i++) {
-                                ret = sscanf(cfg->data + pos, "%hhx%n",
+                                ret = sscanf(cfg->data + data_pos, "%hhx%n",
                                              &val,
                                              &offset);
-                                pos += offset;
+                                data_pos += offset;
                         }
                         continue;
                 }
 
                 if (size > mxt_obj_size(object)) {
-                        dev_err(dev, "Discarding %zu byte(s) in T%u\n",
-                                size - mxt_obj_size(object), type);
+                        /*
+                         * Either we are in fallback mode due to wrong
+                         * config or config from a later fw version,
+                         * or the file is corrupt or hand-edited.
+                         */
+                        dev_warn(dev, "Discarding %zu byte(s) in T%u\n",
+                                 size - mxt_obj_size(object), type);
+                } else if (mxt_obj_size(object) > size) {
+                        /*
+                         * If firmware is upgraded, new bytes may be added to
+                         * end of objects. It is generally forward compatible
+                         * to zero these bytes - previous behaviour will be
+                         * retained. However this does invalidate the CRC and
+                         * will force fallback mode until the configuration is
+                         * updated. We warn here but do nothing else - the
+                         * malloc has zeroed the entire configuration.
+                         */
+                        dev_warn(dev, "Zeroing %zu byte(s) in T%d\n",
+                                 mxt_obj_size(object) - size, type);
                 }
 
                 if (instance >= mxt_obj_instances(object)) {
                         dev_err(dev, "Object instances exceeded!\n");
                         ret = -EINVAL;
-                        goto release;
+                        goto release_mem;
                 }
 
                 reg = object->start_address + mxt_obj_size(object) * instance;
 
                 for (i = 0; i < size; i++) {
-                        ret = sscanf(cfg->data + pos, "%hhx%n",
+                        ret = sscanf(cfg->data + data_pos, "%hhx%n",
                                      &val,
                                      &offset);
                         if (ret != 1) {
                                 dev_err(dev, "Bad format in T%d\n", type);
                                 ret = -EINVAL;
-                                goto release;
+                                goto release_mem;
                         }
-                        pos += offset;
+                        data_pos += offset;
 
                         if (i > mxt_obj_size(object))
                                 continue;
 
-                        ret = mxt_write_reg(data->client, reg + i, val);
-                        if (ret)
-                                goto release;
+                        byte_offset = reg + i - cfg_start_ofs;
 
+                        if ((byte_offset >= 0)
+                            && (byte_offset <= config_mem_size)) {
+                                *(config_mem + byte_offset) = val;
+                        } else {
+                                dev_err(dev, "Bad object: reg:%d, T%d, ofs=%d\n",
+                                        reg, object->type, byte_offset);
+                                ret = -EINVAL;
+                                goto release_mem;
+                        }
                 }
+        }
 
-                /*
-                 * If firmware is upgraded, new bytes may be added to end of
-                 * objects. It is generally forward compatible to zero these
-                 * bytes - previous behaviour will be retained. However
-                 * this does invalidate the CRC and will force a config
-                 * download every time until the configuration is updated.
-                 */
-                if (size < mxt_obj_size(object)) {
-                        dev_info(dev, "Zeroing %zu byte(s) in T%d\n",
-                                 mxt_obj_size(object) - size, type);
+        /* Calculate crc of the received configs (not the raw config file) */
+        if (data->T7_address < cfg_start_ofs) {
+                dev_err(dev, "Bad T7 address, T7addr = %x, config offset %x\n",
+                        data->T7_address, cfg_start_ofs);
+                ret = 0;
+                goto release_mem;
+        }
 
-                        for (i = size + 1; i < mxt_obj_size(object); i++) {
-                                ret = mxt_write_reg(data->client, reg + i, 0);
-                                if (ret)
-                                        goto release;
-                        }
+        calculated_crc = mxt_calculate_crc(config_mem,
+                                           data->T7_address - cfg_start_ofs,
+                                           config_mem_size);
+
+        if (config_crc > 0 && (config_crc != calculated_crc))
+                dev_warn(dev, "Config CRC error, calculated=%06X, file=%06X\n",
+                         calculated_crc, config_crc);
+
+        /* Write configuration as blocks */
+        byte_offset = 0;
+        while (byte_offset < config_mem_size) {
+                size = config_mem_size - byte_offset;
+
+                if (size > MXT_MAX_BLOCK_WRITE)
+                        size = MXT_MAX_BLOCK_WRITE;
+
+                ret = __mxt_write_reg(data->client,
+                                      cfg_start_ofs + byte_offset,
+                                      size, config_mem + byte_offset);
+                if (ret != 0) {
+                        dev_err(dev, "Config write error, ret=%d\n", ret);
+                        goto release_mem;
                 }
+
+                byte_offset += size;
         }
 
         mxt_update_crc(data, MXT_COMMAND_BACKUPNV, MXT_BACKUP_VALUE);
 
         ret = mxt_soft_reset(data);
         if (ret)
-                goto release;
+                goto release_mem;
 
         dev_info(dev, "Config successfully updated\n");
 
+release_mem:
+        kfree(config_mem);
 release:
         release_firmware(cfg);
         return ret;
@@ -1099,6 +1210,7 @@ static int mxt_get_object_table(struct mxt_data *data)
         int error;
         int i;
         u8 reportid;
+        u16 end_address;
 
         table_size = data->info.object_num * sizeof(struct mxt_object);
         object_table = kzalloc(table_size, GFP_KERNEL);
@@ -1116,6 +1228,7 @@ static int mxt_get_object_table(struct mxt_data *data)
 
         /* Valid Report IDs start counting from 1 */
         reportid = 1;
+        data->mem_size = 0;
         for (i = 0; i < data->info.object_num; i++) {
                 struct mxt_object *object = object_table + i;
                 u8 min_id, max_id;
@@ -1143,6 +1256,9 @@ static int mxt_get_object_table(struct mxt_data *data)
                         data->T6_reportid = min_id;
                         data->T6_address = object->start_address;
                         break;
+                case MXT_GEN_POWER_T7:
+                        data->T7_address = object->start_address;
+                        break;
                 case MXT_TOUCH_MULTI_T9:
                         data->T9_reportid_min = min_id;
                         data->T9_reportid_max = max_id;
@@ -1151,6 +1267,12 @@ static int mxt_get_object_table(struct mxt_data *data)
                         data->T19_reportid = min_id;
                         break;
                 }
+
+                end_address = object->start_address
+                        + mxt_obj_size(object) * mxt_obj_instances(object) - 1;
+
+                if (end_address >= data->mem_size)
+                        data->mem_size = end_address + 1;
         }
 
         data->object_table = object_table;