1 files changed, 65 insertions, 2 deletions

diff --git a/drivers/mfd/mc13xxx-spi.c b/drivers/mfd/mc13xxx-spi.c
index 3fcdab3eb8eb..03df422feb76 100644
--- a/drivers/mfd/mc13xxx-spi.c
+++ b/drivers/mfd/mc13xxx-spi.c
@@ -49,10 +49,72 @@ static struct regmap_config mc13xxx_regmap_spi_config = {
         .reg_bits = 7,
         .pad_bits = 1,
         .val_bits = 24,
+        .write_flag_mask = 0x80,
 
         .max_register = MC13XXX_NUMREGS,
 
         .cache_type = REGCACHE_NONE,
+        .use_single_rw = 1,
+};
+
+static int mc13xxx_spi_read(void *context, const void *reg, size_t reg_size,
+                                void *val, size_t val_size)
+{
+        unsigned char w[4] = { *((unsigned char *) reg), 0, 0, 0};
+        unsigned char r[4];
+        unsigned char *p = val;
+        struct device *dev = context;
+        struct spi_device *spi = to_spi_device(dev);
+        struct spi_transfer t = {
+                .tx_buf = w,
+                .rx_buf = r,
+                .len = 4,
+        };
+
+        struct spi_message m;
+        int ret;
+
+        if (val_size != 3 || reg_size != 1)
+                return -ENOTSUPP;
+
+        spi_message_init(&m);
+        spi_message_add_tail(&t, &m);
+        ret = spi_sync(spi, &m);
+
+        memcpy(p, &r[1], 3);
+
+        return ret;
+}
+
+static int mc13xxx_spi_write(void *context, const void *data, size_t count)
+{
+        struct device *dev = context;
+        struct spi_device *spi = to_spi_device(dev);
+
+        if (count != 4)
+                return -ENOTSUPP;
+
+        return spi_write(spi, data, count);
+}
+
+/*
+ * We cannot use regmap-spi generic bus implementation here.
+ * The MC13783 chip will get corrupted if CS signal is deasserted
+ * and on i.Mx31 SoC (the target SoC for MC13783 PMIC) the SPI controller
+ * has the following errata (DSPhl22960):
+ * "The CSPI negates SS when the FIFO becomes empty with
+ * SSCTL= 0. Software cannot guarantee that the FIFO will not
+ * drain because of higher priority interrupts and the
+ * non-realtime characteristics of the operating system. As a
+ * result, the SS will negate before all of the data has been
+ * transferred to/from the peripheral."
+ * We workaround this by accessing the SPI controller with a
+ * single transfert.
+ */
+
+static struct regmap_bus regmap_mc13xxx_bus = {
+        .write = mc13xxx_spi_write,
+        .read = mc13xxx_spi_read,
 };
 
 static int mc13xxx_spi_probe(struct spi_device *spi)
@@ -73,12 +135,13 @@ static int mc13xxx_spi_probe(struct spi_device *spi)
 
         dev_set_drvdata(&spi->dev, mc13xxx);
         spi->mode = SPI_MODE_0 | SPI_CS_HIGH;
-        spi->bits_per_word = 32;
 
         mc13xxx->dev = &spi->dev;
         mutex_init(&mc13xxx->lock);
 
-        mc13xxx->regmap = regmap_init_spi(spi, &mc13xxx_regmap_spi_config);
+        mc13xxx->regmap = regmap_init(&spi->dev, &regmap_mc13xxx_bus, &spi->dev,
+                                        &mc13xxx_regmap_spi_config);
+
         if (IS_ERR(mc13xxx->regmap)) {
                 ret = PTR_ERR(mc13xxx->regmap);
                 dev_err(mc13xxx->dev, "Failed to initialize register map: %d\n",