clk: at91: sckc: add driver compatible with ccf

Add sckc driver compatible with common clock framework. Driver
implements slow clock support for SAM9X60 compatible IPs (in this
list it is also present SAMA7G5's slow clock IP).

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>

drivers/clk/at91/Makefile

@@ -3,7 +3,7 @@
 #
 
 ifdef CONFIG_CLK_CCF
-obj-y += pmc.o
+obj-y += pmc.o sckc.o
 else
 obj-y += compat.o
 endif

drivers/clk/at91/sckc.c

@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Slow clock support for AT91 architectures.
+ *
+ * Copyright (C) 2020 Microchip Technology Inc. and its subsidiaries
+ *
+ * Author: Claudiu Beznea <claudiu.beznea@microchip.com>
+ */
+
+#include <common.h>
+#include <clk-uclass.h>
+#include <dm.h>
+#include <dt-bindings/clk/at91.h>
+#include <linux/clk-provider.h>
+
+#include "pmc.h"
+
+#define UBOOT_DM_CLK_AT91_SAM9X60_TD_SLCK	"at91-sam9x60-td-slck"
+#define UBOOT_DM_CLK_AT91_SCKC			"at91-sckc"
+
+#define AT91_OSC_SEL		BIT(24)
+#define AT91_OSC_SEL_SHIFT	(24)
+
+struct sam9x60_sckc {
+	void __iomem *reg;
+	const char **parent_names;
+	unsigned int num_parents;
+	struct clk clk;
+};
+
+#define to_sam9x60_sckc(c)	container_of(c, struct sam9x60_sckc, clk)
+
+static int sam9x60_sckc_of_xlate(struct clk *clk,
+				 struct ofnode_phandle_args *args)
+{
+	if (args->args_count != 1) {
+		debug("AT91: SCKC: Invalid args_count: %d\n", args->args_count);
+		return -EINVAL;
+	}
+
+	clk->id = AT91_TO_CLK_ID(PMC_TYPE_SLOW, args->args[0]);
+
+	return 0;
+}
+
+static const struct clk_ops sam9x60_sckc_ops = {
+	.of_xlate = sam9x60_sckc_of_xlate,
+	.get_rate = clk_generic_get_rate,
+};
+
+static int sam9x60_td_slck_set_parent(struct clk *clk, struct clk *parent)
+{
+	struct sam9x60_sckc *sckc = to_sam9x60_sckc(clk);
+	u32 i;
+
+	for (i = 0; i < sckc->num_parents; i++) {
+		if (!strcmp(parent->dev->name, sckc->parent_names[i]))
+			break;
+	}
+	if (i == sckc->num_parents)
+		return -EINVAL;
+
+	pmc_update_bits(sckc->reg, 0, AT91_OSC_SEL, (i << AT91_OSC_SEL_SHIFT));
+
+	return 0;
+}
+
+static const struct clk_ops sam9x60_td_slck_ops = {
+	.get_rate = clk_generic_get_rate,
+	.set_parent = sam9x60_td_slck_set_parent,
+};
+
+static struct clk *at91_sam9x60_clk_register_td_slck(struct sam9x60_sckc *sckc,
+		const char *name, const char * const *parent_names,
+		int num_parents)
+{
+	struct clk *clk;
+	int ret = -ENOMEM;
+	u32 val, i;
+
+	if (!sckc || !name || !parent_names || num_parents != 2)
+		return ERR_PTR(-EINVAL);
+
+	sckc->parent_names = kzalloc(sizeof(*sckc->parent_names) * num_parents,
+				     GFP_KERNEL);
+	if (!sckc->parent_names)
+		return ERR_PTR(ret);
+
+	for (i = 0; i < num_parents; i++) {
+		sckc->parent_names[i] = kmemdup(parent_names[i],
+				strlen(parent_names[i]) + 1, GFP_KERNEL);
+		if (!sckc->parent_names[i])
+			goto free;
+	}
+	sckc->num_parents = num_parents;
+
+	pmc_read(sckc->reg, 0, &val);
+	val = (val & AT91_OSC_SEL) >> AT91_OSC_SEL_SHIFT;
+
+	clk = &sckc->clk;
+	ret = clk_register(clk, UBOOT_DM_CLK_AT91_SAM9X60_TD_SLCK, name,
+			   parent_names[val]);
+	if (ret)
+		goto free;
+
+	return clk;
+
+free:
+	for (; i >= 0; i--)
+		kfree(sckc->parent_names[i]);
+	kfree(sckc->parent_names);
+
+	return ERR_PTR(ret);
+}
+
+U_BOOT_DRIVER(at91_sam9x60_td_slck) = {
+	.name = UBOOT_DM_CLK_AT91_SAM9X60_TD_SLCK,
+	.id = UCLASS_CLK,
+	.ops = &sam9x60_td_slck_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};
+
+static int at91_sam9x60_sckc_probe(struct udevice *dev)
+{
+	struct sam9x60_sckc *sckc = dev_get_priv(dev);
+	void __iomem *base = (void *)devfdt_get_addr(dev);
+	const char *slow_rc_osc, *slow_osc;
+	const char *parents[2];
+	struct clk *clk, c;
+	int ret;
+
+	ret = clk_get_by_index(dev, 0, &c);
+	if (ret)
+		return ret;
+	slow_rc_osc = clk_hw_get_name(&c);
+
+	ret = clk_get_by_index(dev, 1, &c);
+	if (ret)
+		return ret;
+	slow_osc = clk_hw_get_name(&c);
+
+	clk = clk_register_fixed_factor(NULL, "md_slck", slow_rc_osc, 0, 1, 1);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+	clk_dm(AT91_TO_CLK_ID(PMC_TYPE_SLOW, 0), clk);
+
+	parents[0] = slow_rc_osc;
+	parents[1] = slow_osc;
+	sckc[1].reg = base;
+	clk = at91_sam9x60_clk_register_td_slck(&sckc[1], "td_slck",
+						parents, 2);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+	clk_dm(AT91_TO_CLK_ID(PMC_TYPE_SLOW, 1), clk);
+
+	return 0;
+}
+
+static const struct udevice_id sam9x60_sckc_ids[] = {
+	{ .compatible = "microchip,sam9x60-sckc" },
+	{ /* Sentinel. */ },
+};
+
+U_BOOT_DRIVER(at91_sckc) = {
+	.name = UBOOT_DM_CLK_AT91_SCKC,
+	.id = UCLASS_CLK,
+	.of_match = sam9x60_sckc_ids,
+	.priv_auto_alloc_size = sizeof(struct sam9x60_sckc) * 2,
+	.ops = &sam9x60_sckc_ops,
+	.probe = at91_sam9x60_sckc_probe,
+	.flags = DM_FLAG_PRE_RELOC,
+};