rtc: rv3028: add clkout support

rv3028 provides clkout (enabled by default). Add clkout
to clock framework source and control from device tree for
variable frequency with enable and disable functionality.

Signed-off-by: Parthiban Nallathambi <pn@denx.de>
Link: https://lore.kernel.org/r/20191018100425.1687979-1-pn@denx.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-rv3028.c b/drivers/rtc/rtc-rv3028.c
index 2b31666..6b7b3a6 100644 (file)
--- a/drivers/rtc/rtc-rv3028.c
+++ b/drivers/rtc/rtc-rv3028.c
@@ -8,6 +8,7 @@
  *
  */
 
+#include <linux/clk-provider.h>
 #include <linux/bcd.h>
 #include <linux/bitops.h>
 #include <linux/i2c.h>
@@ -52,6 +53,11 @@
 #define RV3028_STATUS_CLKF             BIT(6)
 #define RV3028_STATUS_EEBUSY           BIT(7)
 
+#define RV3028_CLKOUT_FD_MASK          GENMASK(2, 0)
+#define RV3028_CLKOUT_PORIE            BIT(3)
+#define RV3028_CLKOUT_CLKSY            BIT(6)
+#define RV3028_CLKOUT_CLKOE            BIT(7)
+
 #define RV3028_CTRL1_EERD              BIT(3)
 #define RV3028_CTRL1_WADA              BIT(5)
 
@@ -84,6 +90,9 @@ struct rv3028_data {
        struct regmap *regmap;
        struct rtc_device *rtc;
        enum rv3028_type type;
+#ifdef CONFIG_COMMON_CLK
+       struct clk_hw clkout_hw;
+#endif
 };
 
 static u16 rv3028_trickle_resistors[] = {1000, 3000, 6000, 11000};
@@ -581,6 +590,140 @@ restore_eerd:
        return ret;
 }
 
+#ifdef CONFIG_COMMON_CLK
+#define clkout_hw_to_rv3028(hw) container_of(hw, struct rv3028_data, clkout_hw)
+
+static int clkout_rates[] = {
+       32768,
+       8192,
+       1024,
+       64,
+       32,
+       1,
+};
+
+static unsigned long rv3028_clkout_recalc_rate(struct clk_hw *hw,
+                                              unsigned long parent_rate)
+{
+       int clkout, ret;
+       struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+       ret = regmap_read(rv3028->regmap, RV3028_CLKOUT, &clkout);
+       if (ret < 0)
+               return 0;
+
+       clkout &= RV3028_CLKOUT_FD_MASK;
+       return clkout_rates[clkout];
+}
+
+static long rv3028_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
+                                    unsigned long *prate)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
+               if (clkout_rates[i] <= rate)
+                       return clkout_rates[i];
+
+       return 0;
+}
+
+static int rv3028_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
+                                 unsigned long parent_rate)
+{
+       int i, ret;
+       struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+       ret = regmap_write(rv3028->regmap, RV3028_CLKOUT, 0x0);
+       if (ret < 0)
+               return ret;
+
+       for (i = 0; i < ARRAY_SIZE(clkout_rates); i++) {
+               if (clkout_rates[i] == rate) {
+                       ret = regmap_update_bits(rv3028->regmap,
+                                                RV3028_CLKOUT,
+                                                RV3028_CLKOUT_FD_MASK, i);
+                       if (ret < 0)
+                               return ret;
+
+                       return regmap_write(rv3028->regmap, RV3028_CLKOUT,
+                               RV3028_CLKOUT_CLKSY | RV3028_CLKOUT_CLKOE);
+               }
+       }
+
+       return -EINVAL;
+}
+
+static int rv3028_clkout_prepare(struct clk_hw *hw)
+{
+       struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+       return regmap_write(rv3028->regmap, RV3028_CLKOUT,
+                           RV3028_CLKOUT_CLKSY | RV3028_CLKOUT_CLKOE);
+}
+
+static void rv3028_clkout_unprepare(struct clk_hw *hw)
+{
+       struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+       regmap_write(rv3028->regmap, RV3028_CLKOUT, 0x0);
+       regmap_update_bits(rv3028->regmap, RV3028_STATUS,
+                          RV3028_STATUS_CLKF, 0);
+}
+
+static int rv3028_clkout_is_prepared(struct clk_hw *hw)
+{
+       int clkout, ret;
+       struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+       ret = regmap_read(rv3028->regmap, RV3028_CLKOUT, &clkout);
+       if (ret < 0)
+               return ret;
+
+       return !!(clkout & RV3028_CLKOUT_CLKOE);
+}
+
+static const struct clk_ops rv3028_clkout_ops = {
+       .prepare = rv3028_clkout_prepare,
+       .unprepare = rv3028_clkout_unprepare,
+       .is_prepared = rv3028_clkout_is_prepared,
+       .recalc_rate = rv3028_clkout_recalc_rate,
+       .round_rate = rv3028_clkout_round_rate,
+       .set_rate = rv3028_clkout_set_rate,
+};
+
+static int rv3028_clkout_register_clk(struct rv3028_data *rv3028,
+                                     struct i2c_client *client)
+{
+       int ret;
+       struct clk *clk;
+       struct clk_init_data init;
+       struct device_node *node = client->dev.of_node;
+
+       ret = regmap_update_bits(rv3028->regmap, RV3028_STATUS,
+                                RV3028_STATUS_CLKF, 0);
+       if (ret < 0)
+               return ret;
+
+       init.name = "rv3028-clkout";
+       init.ops = &rv3028_clkout_ops;
+       init.flags = 0;
+       init.parent_names = NULL;
+       init.num_parents = 0;
+       rv3028->clkout_hw.init = &init;
+
+       /* optional override of the clockname */
+       of_property_read_string(node, "clock-output-names", &init.name);
+
+       /* register the clock */
+       clk = devm_clk_register(&client->dev, &rv3028->clkout_hw);
+       if (!IS_ERR(clk))
+               of_clk_add_provider(node, of_clk_src_simple_get, clk);
+
+       return 0;
+}
+#endif
+
 static struct rtc_class_ops rv3028_rtc_ops = {
        .read_time = rv3028_get_time,
        .set_time = rv3028_set_time,
@@ -708,6 +851,9 @@ static int rv3028_probe(struct i2c_client *client)
 
        rv3028->rtc->max_user_freq = 1;
 
+#ifdef CONFIG_COMMON_CLK
+       rv3028_clkout_register_clk(rv3028, client);
+#endif
        return 0;
 }