i2c: designware-pci: set ideal HCNT, LCNT and SDA hold time value

On Intel BayTrail, there was case whereby the resulting fast mode
bus speed becomes slower (~20% slower compared to expected speed)
if using the HCNT/LCNT calculated in the core layer. Thus, this
patch is added to allow pci glue layer to pass in optimal
HCNT/LCNT/SDA hold time values to core layer since the core
layer supports cofigurable HCNT/LCNT/SDA hold time values now.

Signed-off-by: Chew, Chiau Ee <chiau.ee.chew@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 28 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-designware-pcidrv.c b/drivers/i2c/busses/i2c-designware-pcidrv.c
index 094509bcc089..91d468f8cd39 100644
--- a/drivers/i2c/busses/i2c-designware-pcidrv.c
+++ b/drivers/i2c/busses/i2c-designware-pcidrv.c
@@ -58,6 +58,14 @@ enum dw_pci_ctl_id_t {
         baytrail,
 };
 
+struct dw_scl_sda_cfg {
+        u32 ss_hcnt;
+        u32 fs_hcnt;
+        u32 ss_lcnt;
+        u32 fs_lcnt;
+        u32 sda_hold;
+};
+
 struct dw_pci_controller {
         u32 bus_num;
         u32 bus_cfg;
@@ -65,6 +73,7 @@ struct dw_pci_controller {
         u32 rx_fifo_depth;
         u32 clk_khz;
         u32 functionality;
+        struct dw_scl_sda_cfg *scl_sda_cfg;
 };
 
 #define INTEL_MID_STD_CFG  (DW_IC_CON_MASTER |                  \
@@ -77,6 +86,15 @@ struct dw_pci_controller {
                                         I2C_FUNC_SMBUS_WORD_DATA |      \
                                         I2C_FUNC_SMBUS_I2C_BLOCK)
 
+/* BayTrail HCNT/LCNT/SDA hold time */
+static struct dw_scl_sda_cfg byt_config = {
+        .ss_hcnt = 0x200,
+        .fs_hcnt = 0x55,
+        .ss_lcnt = 0x200,
+        .fs_lcnt = 0x99,
+        .sda_hold = 0x6,
+};
+
 static struct  dw_pci_controller  dw_pci_controllers[] = {
         [moorestown_0] = {
                 .bus_num     = 0,
@@ -148,6 +166,7 @@ static struct  dw_pci_controller  dw_pci_controllers[] = {
                 .rx_fifo_depth = 32,
                 .clk_khz = 100000,
                 .functionality = I2C_FUNC_10BIT_ADDR,
+                .scl_sda_cfg = &byt_config,
         },
 };
 static struct i2c_algorithm i2c_dw_algo = {
@@ -187,6 +206,7 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev,
         struct i2c_adapter *adap;
         int r;
         struct  dw_pci_controller *controller;
+        struct dw_scl_sda_cfg *cfg;
 
         if (id->driver_data >= ARRAY_SIZE(dw_pci_controllers)) {
                 dev_err(&pdev->dev, "%s: invalid driver data %ld\n", __func__,
@@ -224,6 +244,14 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev,
                                 DW_DEFAULT_FUNCTIONALITY;
 
         dev->master_cfg =  controller->bus_cfg;
+        if (controller->scl_sda_cfg) {
+                cfg = controller->scl_sda_cfg;
+                dev->ss_hcnt = cfg->ss_hcnt;
+                dev->fs_hcnt = cfg->fs_hcnt;
+                dev->ss_lcnt = cfg->ss_lcnt;
+                dev->fs_lcnt = cfg->fs_lcnt;
+                dev->sda_hold_time = cfg->sda_hold;
+        }
 
         pci_set_drvdata(pdev, dev);