i2c: brcmstb: Adding support for CM and DSL SoCs

Broadcoms DSL, CM (cable modem)and STB I2C core implementation have
8 data in/out registers that can transfer 8 bytes or 32 bytes max.
Cable and DSL "Peripheral" i2c cores use single byte per data
register and the STB can use 4 byte per data register transfer.
Adding support to take care of this difference. Accordingly added
the compatible string for SoCs using the "Peripheral" I2C block.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

2 files changed, 57 insertions, 25 deletions

diff --git a/Documentation/devicetree/bindings/i2c/i2c-brcmstb.txt b/Documentation/devicetree/bindings/i2c/i2c-brcmstb.txt
index d6f724efdcf2..aeceaceba3c5 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-brcmstb.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-brcmstb.txt
@@ -2,7 +2,7 @@ Broadcom stb bsc iic master controller
 
 Required properties:
 
-- compatible: should be "brcm,brcmstb-i2c"
+- compatible: should be "brcm,brcmstb-i2c" or "brcm,brcmper-i2c"
 - clock-frequency: 32-bit decimal value of iic master clock freqency in Hz
                    valid values are 375000, 390000, 187500, 200000
                    93750, 97500, 46875 and 50000
diff --git a/drivers/i2c/busses/i2c-brcmstb.c b/drivers/i2c/busses/i2c-brcmstb.c
index 8e9637eea512..3711df1d4526 100644
--- a/drivers/i2c/busses/i2c-brcmstb.c
+++ b/drivers/i2c/busses/i2c-brcmstb.c
@@ -25,13 +25,16 @@
 #include <linux/version.h>
 
 #define N_DATA_REGS                                     8
-#define N_DATA_BYTES                                    (N_DATA_REGS * 4)
 
-/* BSC count register field definitions */
-#define BSC_CNT_REG1_MASK                               0x0000003f
-#define BSC_CNT_REG1_SHIFT                              0
-#define BSC_CNT_REG2_MASK                               0x00000fc0
-#define BSC_CNT_REG2_SHIFT                              6
+/*
+ * PER_I2C/BSC count register mask depends on 1 byte/4 byte data register
+ * size. Cable modem and DSL SoCs with Peripheral i2c cores use 1 byte per
+ * data register whereas STB SoCs use 4 byte per data register transfer,
+ * account for this difference in total count per transaction and mask to
+ * use.
+ */
+#define BSC_CNT_REG1_MASK(nb)   (nb == 1 ? GENMASK(3, 0) : GENMASK(5, 0))
+#define BSC_CNT_REG1_SHIFT      0
 
 /* BSC CTL register field definitions */
 #define BSC_CTL_REG_DTF_MASK                            0x00000003
@@ -41,7 +44,7 @@
 #define BSC_CTL_REG_INT_EN_SHIFT                        6
 #define BSC_CTL_REG_DIV_CLK_MASK                        0x00000080
 
-/* BSC_IIC_ENABLE r/w enable and interrupt field defintions */
+/* BSC_IIC_ENABLE r/w enable and interrupt field definitions */
 #define BSC_IIC_EN_RESTART_MASK                         0x00000040
 #define BSC_IIC_EN_NOSTART_MASK                         0x00000020
 #define BSC_IIC_EN_NOSTOP_MASK                          0x00000010
@@ -169,6 +172,7 @@ struct brcmstb_i2c_dev {
         struct completion done;
         bool is_suspended;
         u32 clk_freq_hz;
+        int data_regsz;
 };
 
 /* register accessors for both be and le cpu arch */
@@ -186,6 +190,16 @@ struct brcmstb_i2c_dev {
 #define bsc_writel(_dev, _val, _reg)                                    \
         __bsc_writel(_val, _dev->base + offsetof(struct bsc_regs, _reg))
 
+static inline int brcmstb_i2c_get_xfersz(struct brcmstb_i2c_dev *dev)
+{
+        return (N_DATA_REGS * dev->data_regsz);
+}
+
+static inline int brcmstb_i2c_get_data_regsz(struct brcmstb_i2c_dev *dev)
+{
+        return dev->data_regsz;
+}
+
 static void brcmstb_i2c_enable_disable_irq(struct brcmstb_i2c_dev *dev,
                                            bool int_en)
 {
@@ -323,14 +337,16 @@ static int brcmstb_i2c_xfer_bsc_data(struct brcmstb_i2c_dev *dev,
                                      u8 *buf, unsigned int len,
                                      struct i2c_msg *pmsg)
 {
-        int cnt, byte, rc;
+        int cnt, byte, i, rc;
         enum bsc_xfer_cmd cmd;
         u32 ctl_reg;
         struct bsc_regs *pi2creg = dev->bsc_regmap;
         int no_ack = pmsg->flags & I2C_M_IGNORE_NAK;
+        int data_regsz = brcmstb_i2c_get_data_regsz(dev);
+        int xfersz = brcmstb_i2c_get_xfersz(dev);
 
         /* see if the transaction needs to check NACK conditions */
-        if (no_ack || len <= N_DATA_BYTES) {
+        if (no_ack || len <= xfersz) {
                 cmd = (pmsg->flags & I2C_M_RD) ? CMD_RD_NOACK
                         : CMD_WR_NOACK;
                 pi2creg->ctlhi_reg |= BSC_CTLHI_REG_IGNORE_ACK_MASK;
@@ -348,20 +364,22 @@ static int brcmstb_i2c_xfer_bsc_data(struct brcmstb_i2c_dev *dev,
                 pi2creg->ctl_reg = ctl_reg | DTF_RD_MASK;
 
         /* set the read/write length */
-        bsc_writel(dev, BSC_CNT_REG1_MASK & (len << BSC_CNT_REG1_SHIFT),
-                   cnt_reg);
+        bsc_writel(dev, BSC_CNT_REG1_MASK(data_regsz) &
+                   (len << BSC_CNT_REG1_SHIFT), cnt_reg);
 
         /* Write data into data_in register */
+
         if (cmd == CMD_WR || cmd == CMD_WR_NOACK) {
-                for (cnt = 0; cnt < len; cnt += 4) {
+                for (cnt = 0, i = 0; cnt < len; cnt += data_regsz, i++) {
                         u32 word = 0;
 
-                        for (byte = 0; byte < 4; byte++) {
-                                word >>= 8;
+                        for (byte = 0; byte < data_regsz; byte++) {
+                                word >>= BITS_PER_BYTE;
                                 if ((cnt + byte) < len)
-                                        word |= buf[cnt + byte] << 24;
+                                        word |= buf[cnt + byte] <<
+                                        (BITS_PER_BYTE * (data_regsz - 1));
                         }
-                        bsc_writel(dev, word, data_in[cnt >> 2]);
+                        bsc_writel(dev, word, data_in[i]);
                 }
         }
 
@@ -373,14 +391,15 @@ static int brcmstb_i2c_xfer_bsc_data(struct brcmstb_i2c_dev *dev,
                 return rc;
         }
 
+        /* Read data from data_out register */
         if (cmd == CMD_RD || cmd == CMD_RD_NOACK) {
-                for (cnt = 0; cnt < len; cnt += 4) {
-                        u32 data = bsc_readl(dev, data_out[cnt >> 2]);
+                for (cnt = 0, i = 0; cnt < len; cnt += data_regsz, i++) {
+                        u32 data = bsc_readl(dev, data_out[i]);
 
-                        for (byte = 0; byte < 4 &&
+                        for (byte = 0; byte < data_regsz &&
                                      (byte + cnt) < len; byte++) {
                                 buf[cnt + byte] = data & 0xff;
-                                data >>= 8;
+                                data >>= BITS_PER_BYTE;
                         }
                 }
         }
@@ -448,6 +467,7 @@ static int brcmstb_i2c_xfer(struct i2c_adapter *adapter,
         int bytes_to_xfer;
         u8 *tmp_buf;
         int len = 0;
+        int xfersz = brcmstb_i2c_get_xfersz(dev);
 
         if (dev->is_suspended)
                 return -EBUSY;
@@ -482,9 +502,9 @@ static int brcmstb_i2c_xfer(struct i2c_adapter *adapter,
 
                 /* Perform data transfer */
                 while (len) {
-                        bytes_to_xfer = min(len, N_DATA_BYTES);
+                        bytes_to_xfer = min(len, xfersz);
 
-                        if (len <= N_DATA_BYTES && i == (num - 1))
+                        if (len <= xfersz && i == (num - 1))
                                 brcmstb_set_i2c_start_stop(dev,
                                                            ~(COND_START_STOP));
 
@@ -542,8 +562,12 @@ static void brcmstb_i2c_set_bus_speed(struct brcmstb_i2c_dev *dev)
 
 static void brcmstb_i2c_set_bsc_reg_defaults(struct brcmstb_i2c_dev *dev)
 {
-        /* 4 byte data register */
-        dev->bsc_regmap->ctlhi_reg = BSC_CTLHI_REG_DATAREG_SIZE_MASK;
+        if (brcmstb_i2c_get_data_regsz(dev) == sizeof(u32))
+                /* set 4 byte data in/out xfers  */
+                dev->bsc_regmap->ctlhi_reg = BSC_CTLHI_REG_DATAREG_SIZE_MASK;
+        else
+                dev->bsc_regmap->ctlhi_reg &= ~BSC_CTLHI_REG_DATAREG_SIZE_MASK;
+
         bsc_writel(dev, dev->bsc_regmap->ctlhi_reg, ctlhi_reg);
         /* set bus speed */
         brcmstb_i2c_set_bus_speed(dev);
@@ -608,6 +632,13 @@ static int brcmstb_i2c_probe(struct platform_device *pdev)
                 dev->clk_freq_hz = bsc_clk[0].hz;
         }
 
+        /* set the data in/out register size for compatible SoCs */
+        if (of_device_is_compatible(dev->device->of_node,
+                                    "brcmstb,brcmper-i2c"))
+                dev->data_regsz = sizeof(u8);
+        else
+                dev->data_regsz = sizeof(u32);
+
         brcmstb_i2c_set_bsc_reg_defaults(dev);
 
         /* Add the i2c adapter */
@@ -674,6 +705,7 @@ static SIMPLE_DEV_PM_OPS(brcmstb_i2c_pm, brcmstb_i2c_suspend,
 
 static const struct of_device_id brcmstb_i2c_of_match[] = {
         {.compatible = "brcm,brcmstb-i2c"},
+        {.compatible = "brcm,brcmper-i2c"},
         {},
 };
 MODULE_DEVICE_TABLE(of, brcmstb_i2c_of_match);