iio: adc: ad7192: Add clock provider

Internal clock of AD719X devices can be made available on MCLK2 pin. Add
clock provider to support this functionality when clock cells property
is present.
Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://patch.msgid.link/20240717212535.8348-5-alisa.roman@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7192.c

@@ -8,6 +8,7 @@
 #include <linux/interrupt.h>
 #include <linux/bitfield.h>
 #include <linux/clk.h>
+#include <linux/clk-provider.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
@@ -201,6 +202,7 @@ struct ad7192_chip_info {
 struct ad7192_state {
 	const struct ad7192_chip_info	*chip_info;
 	struct clk			*mclk;
+	struct clk_hw			int_clk_hw;
 	u16				int_vref_mv;
 	u32				aincom_mv;
 	u32				fclk;
@@ -406,6 +408,91 @@ static const char *const ad7192_clock_names[] = {
 	"mclk"
 };
 
+static struct ad7192_state *clk_hw_to_ad7192(struct clk_hw *hw)
+{
+	return container_of(hw, struct ad7192_state, int_clk_hw);
+}
+
+static unsigned long ad7192_clk_recalc_rate(struct clk_hw *hw,
+					    unsigned long parent_rate)
+{
+	return AD7192_INT_FREQ_MHZ;
+}
+
+static int ad7192_clk_output_is_enabled(struct clk_hw *hw)
+{
+	struct ad7192_state *st = clk_hw_to_ad7192(hw);
+
+	return st->clock_sel == AD7192_CLK_INT_CO;
+}
+
+static int ad7192_clk_prepare(struct clk_hw *hw)
+{
+	struct ad7192_state *st = clk_hw_to_ad7192(hw);
+	int ret;
+
+	st->mode &= ~AD7192_MODE_CLKSRC_MASK;
+	st->mode |= AD7192_CLK_INT_CO;
+
+	ret = ad_sd_write_reg(&st->sd, AD7192_REG_MODE, 3, st->mode);
+	if (ret)
+		return ret;
+
+	st->clock_sel = AD7192_CLK_INT_CO;
+
+	return 0;
+}
+
+static void ad7192_clk_unprepare(struct clk_hw *hw)
+{
+	struct ad7192_state *st = clk_hw_to_ad7192(hw);
+	int ret;
+
+	st->mode &= ~AD7192_MODE_CLKSRC_MASK;
+	st->mode |= AD7192_CLK_INT;
+
+	ret = ad_sd_write_reg(&st->sd, AD7192_REG_MODE, 3, st->mode);
+	if (ret)
+		return;
+
+	st->clock_sel = AD7192_CLK_INT;
+}
+
+static const struct clk_ops ad7192_int_clk_ops = {
+	.recalc_rate = ad7192_clk_recalc_rate,
+	.is_enabled = ad7192_clk_output_is_enabled,
+	.prepare = ad7192_clk_prepare,
+	.unprepare = ad7192_clk_unprepare,
+};
+
+static int ad7192_register_clk_provider(struct ad7192_state *st)
+{
+	struct device *dev = &st->sd.spi->dev;
+	struct clk_init_data init = {};
+	int ret;
+
+	if (!IS_ENABLED(CONFIG_COMMON_CLK))
+		return 0;
+
+	if (!device_property_present(dev, "#clock-cells"))
+		return 0;
+
+	init.name = devm_kasprintf(dev, GFP_KERNEL, "%s-clk",
+				   fwnode_get_name(dev_fwnode(dev)));
+	if (!init.name)
+		return -ENOMEM;
+
+	init.ops = &ad7192_int_clk_ops;
+
+	st->int_clk_hw.init = &init;
+	ret = devm_clk_hw_register(dev, &st->int_clk_hw);
+	if (ret)
+		return ret;
+
+	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
+					   &st->int_clk_hw);
+}
+
 static int ad7192_clock_setup(struct ad7192_state *st)
 {
 	struct device *dev = &st->sd.spi->dev;
@@ -446,6 +533,11 @@ static int ad7192_clock_setup(struct ad7192_state *st)
 	if (ret < 0) {
 		st->clock_sel = AD7192_CLK_INT;
 		st->fclk = AD7192_INT_FREQ_MHZ;
+
+		ret = ad7192_register_clk_provider(st);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to register clock provider\n");
 		return 0;
 	}