i2c: stm32f7: SYSCFG Fast Mode Plus support for I2C STM32F7

Read SYSCFG bindings to set Fast Mode Plus bits if Fast Mode Plus
speed is selected.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 35 insertions, 3 deletions

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 62d023e737d9..e9f0c0bd774d 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -21,12 +21,14 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/iopoll.h>
+#include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/regmap.h>
 #include <linux/reset.h>
 #include <linux/slab.h>
 
@@ -276,6 +278,7 @@ struct stm32f7_i2c_msg {
  * slave)
  * @dma: dma data
  * @use_dma: boolean to know if dma is used in the current transfer
+ * @regmap: holds SYSCFG phandle for Fast Mode Plus bits
  */
 struct stm32f7_i2c_dev {
         struct i2c_adapter adap;
@@ -296,6 +299,7 @@ struct stm32f7_i2c_dev {
         bool master_mode;
         struct stm32_i2c_dma *dma;
         bool use_dma;
+        struct regmap *regmap;
 };
 
 /**
@@ -1763,6 +1767,30 @@ static int stm32f7_i2c_unreg_slave(struct i2c_client *slave)
         return 0;
 }
 
+static int stm32f7_i2c_setup_fm_plus_bits(struct platform_device *pdev,
+                                          struct stm32f7_i2c_dev *i2c_dev)
+{
+        struct device_node *np = pdev->dev.of_node;
+        int ret;
+        u32 reg, mask;
+
+        i2c_dev->regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg-fmp");
+        if (IS_ERR(i2c_dev->regmap)) {
+                /* Optional */
+                return 0;
+        }
+
+        ret = of_property_read_u32_index(np, "st,syscfg-fmp", 1, &reg);
+        if (ret)
+                return ret;
+
+        ret = of_property_read_u32_index(np, "st,syscfg-fmp", 2, &mask);
+        if (ret)
+                return ret;
+
+        return regmap_update_bits(i2c_dev->regmap, reg, mask, mask);
+}
+
 static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
 {
         return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SLAVE |
@@ -1828,12 +1856,16 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
         i2c_dev->speed = STM32_I2C_SPEED_STANDARD;
         ret = device_property_read_u32(&pdev->dev, "clock-frequency",
                                        &clk_rate);
-        if (!ret && clk_rate >= 1000000)
+        if (!ret && clk_rate >= 1000000) {
                 i2c_dev->speed = STM32_I2C_SPEED_FAST_PLUS;
-        else if (!ret && clk_rate >= 400000)
+                ret = stm32f7_i2c_setup_fm_plus_bits(pdev, i2c_dev);
+                if (ret)
+                        goto clk_free;
+        } else if (!ret && clk_rate >= 400000) {
                 i2c_dev->speed = STM32_I2C_SPEED_FAST;
-        else if (!ret && clk_rate >= 100000)
+        } else if (!ret && clk_rate >= 100000) {
                 i2c_dev->speed = STM32_I2C_SPEED_STANDARD;
+        }
 
         rst = devm_reset_control_get(&pdev->dev, NULL);
         if (IS_ERR(rst)) {