clk: at91: add I2S clock mux driver

This driver is a simple muxing driver that controls the
I2S's clock input by using syscon/regmap to change the parent.
The available inputs can be peripheral clock and generated clock.

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
[sboyd@kernel.org: Fix SPDX tag comment style]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

3 files changed, 121 insertions, 0 deletions

diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index 1254bf9d91b4..903f23c309df 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -27,6 +27,7 @@ config SOC_SAMA5D2
         select HAVE_AT91_H32MX
         select HAVE_AT91_GENERATED_CLK
         select HAVE_AT91_AUDIO_PLL
+        select HAVE_AT91_I2S_MUX_CLK
         select PINCTRL_AT91PIO4
         help
           Select this if ou are using one of Microchip's SAMA5D2 family SoC.
@@ -129,6 +130,9 @@ config HAVE_AT91_GENERATED_CLK
 config HAVE_AT91_AUDIO_PLL
         bool
 
+config HAVE_AT91_I2S_MUX_CLK
+        bool
+
 config SOC_SAM_V4_V5
         bool
 
diff --git a/drivers/clk/at91/Makefile b/drivers/clk/at91/Makefile
index 082596f37c1d..facc169ebb68 100644
--- a/drivers/clk/at91/Makefile
+++ b/drivers/clk/at91/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_HAVE_AT91_USB_CLK)		+= clk-usb.o
 obj-$(CONFIG_HAVE_AT91_SMD)             += clk-smd.o
 obj-$(CONFIG_HAVE_AT91_H32MX)           += clk-h32mx.o
 obj-$(CONFIG_HAVE_AT91_GENERATED_CLK)   += clk-generated.o
+obj-$(CONFIG_HAVE_AT91_I2S_MUX_CLK)     += clk-i2s-mux.o
diff --git a/drivers/clk/at91/clk-i2s-mux.c b/drivers/clk/at91/clk-i2s-mux.c
new file mode 100644
index 000000000000..f0c3c3079f04
--- /dev/null
+++ b/drivers/clk/at91/clk-i2s-mux.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2018 Microchip Technology Inc,
+ *                     Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
+ *
+ *
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/of.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#include <soc/at91/atmel-sfr.h>
+
+#define I2S_BUS_NR      2
+
+struct clk_i2s_mux {
+        struct clk_hw hw;
+        struct regmap *regmap;
+        u8 bus_id;
+};
+
+#define to_clk_i2s_mux(hw) container_of(hw, struct clk_i2s_mux, hw)
+
+static u8 clk_i2s_mux_get_parent(struct clk_hw *hw)
+{
+        struct clk_i2s_mux *mux = to_clk_i2s_mux(hw);
+        u32 val;
+
+        regmap_read(mux->regmap, AT91_SFR_I2SCLKSEL, &val);
+
+        return (val & BIT(mux->bus_id)) >> mux->bus_id;
+}
+
+static int clk_i2s_mux_set_parent(struct clk_hw *hw, u8 index)
+{
+        struct clk_i2s_mux *mux = to_clk_i2s_mux(hw);
+
+        return regmap_update_bits(mux->regmap, AT91_SFR_I2SCLKSEL,
+                                  BIT(mux->bus_id), index << mux->bus_id);
+}
+
+static const struct clk_ops clk_i2s_mux_ops = {
+        .get_parent = clk_i2s_mux_get_parent,
+        .set_parent = clk_i2s_mux_set_parent,
+        .determine_rate = __clk_mux_determine_rate,
+};
+
+static struct clk_hw * __init
+at91_clk_i2s_mux_register(struct regmap *regmap, const char *name,
+                          const char * const *parent_names,
+                          unsigned int num_parents, u8 bus_id)
+{
+        struct clk_init_data init = {};
+        struct clk_i2s_mux *i2s_ck;
+        int ret;
+
+        i2s_ck = kzalloc(sizeof(*i2s_ck), GFP_KERNEL);
+        if (!i2s_ck)
+                return ERR_PTR(-ENOMEM);
+
+        init.name = name;
+        init.ops = &clk_i2s_mux_ops;
+        init.parent_names = parent_names;
+        init.num_parents = num_parents;
+
+        i2s_ck->hw.init = &init;
+        i2s_ck->bus_id = bus_id;
+        i2s_ck->regmap = regmap;
+
+        ret = clk_hw_register(NULL, &i2s_ck->hw);
+        if (ret) {
+                kfree(i2s_ck);
+                return ERR_PTR(ret);
+        }
+
+        return &i2s_ck->hw;
+}
+
+static void __init of_sama5d2_clk_i2s_mux_setup(struct device_node *np)
+{
+        struct regmap *regmap_sfr;
+        u8 bus_id;
+        const char *parent_names[2];
+        struct device_node *i2s_mux_np;
+        struct clk_hw *hw;
+        int ret;
+
+        regmap_sfr = syscon_regmap_lookup_by_compatible("atmel,sama5d2-sfr");
+        if (IS_ERR(regmap_sfr))
+                return;
+
+        for_each_child_of_node(np, i2s_mux_np) {
+                if (of_property_read_u8(i2s_mux_np, "reg", &bus_id))
+                        continue;
+
+                if (bus_id > I2S_BUS_NR)
+                        continue;
+
+                ret = of_clk_parent_fill(i2s_mux_np, parent_names, 2);
+                if (ret != 2)
+                        continue;
+
+                hw = at91_clk_i2s_mux_register(regmap_sfr, i2s_mux_np->name,
+                                               parent_names, 2, bus_id);
+                if (IS_ERR(hw))
+                        continue;
+
+                of_clk_add_hw_provider(i2s_mux_np, of_clk_hw_simple_get, hw);
+        }
+}
+
+CLK_OF_DECLARE(sama5d2_clk_i2s_mux, "atmel,sama5d2-clk-i2s-mux",
+               of_sama5d2_clk_i2s_mux_setup);