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authorLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>2013-10-17 23:54:07 +0200
committerMike Turquette <mturquette@linaro.org>2013-12-12 19:23:59 -0800
commitf94859c215b6d977794108a1a9a101239e393c09 (patch)
tree8de13d7d3cd0d6a27219207e388037fd3407f16c /drivers/clk/shmobile
parentabe844aa5bb50444ac3e02aed89b431823d6ad56 (diff)
clk: shmobile: Add MSTP clock support
MSTP clocks are gate clocks controlled through a register that handles up to 32 clocks. The register is often sparsely populated. Those clocks are found on Renesas ARM SoCs. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Mike Turquette <mturquette@linaro.org>
Diffstat (limited to 'drivers/clk/shmobile')
-rw-r--r--drivers/clk/shmobile/Makefile1
-rw-r--r--drivers/clk/shmobile/clk-mstp.c229
2 files changed, 230 insertions, 0 deletions
diff --git a/drivers/clk/shmobile/Makefile b/drivers/clk/shmobile/Makefile
index 2e4a1197aa0a..706adc6ae70c 100644
--- a/drivers/clk/shmobile/Makefile
+++ b/drivers/clk/shmobile/Makefile
@@ -1,6 +1,7 @@
obj-$(CONFIG_ARCH_R8A7790) += clk-rcar-gen2.o
obj-$(CONFIG_ARCH_R8A7791) += clk-rcar-gen2.o
obj-$(CONFIG_ARCH_SHMOBILE_MULTI) += clk-div6.o
+obj-$(CONFIG_ARCH_SHMOBILE_MULTI) += clk-mstp.o
# for emply built-in.o
obj-n := dummy
diff --git a/drivers/clk/shmobile/clk-mstp.c b/drivers/clk/shmobile/clk-mstp.c
new file mode 100644
index 000000000000..e576b60de20e
--- /dev/null
+++ b/drivers/clk/shmobile/clk-mstp.c
@@ -0,0 +1,229 @@
+/*
+ * R-Car MSTP clocks
+ *
+ * Copyright (C) 2013 Ideas On Board SPRL
+ *
+ * Contact: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/spinlock.h>
+
+/*
+ * MSTP clocks. We can't use standard gate clocks as we need to poll on the
+ * status register when enabling the clock.
+ */
+
+#define MSTP_MAX_CLOCKS 32
+
+/**
+ * struct mstp_clock_group - MSTP gating clocks group
+ *
+ * @data: clocks in this group
+ * @smstpcr: module stop control register
+ * @mstpsr: module stop status register (optional)
+ * @lock: protects writes to SMSTPCR
+ */
+struct mstp_clock_group {
+ struct clk_onecell_data data;
+ void __iomem *smstpcr;
+ void __iomem *mstpsr;
+ spinlock_t lock;
+};
+
+/**
+ * struct mstp_clock - MSTP gating clock
+ * @hw: handle between common and hardware-specific interfaces
+ * @bit_index: control bit index
+ * @group: MSTP clocks group
+ */
+struct mstp_clock {
+ struct clk_hw hw;
+ u32 bit_index;
+ struct mstp_clock_group *group;
+};
+
+#define to_mstp_clock(_hw) container_of(_hw, struct mstp_clock, hw)
+
+static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
+{
+ struct mstp_clock *clock = to_mstp_clock(hw);
+ struct mstp_clock_group *group = clock->group;
+ u32 bitmask = BIT(clock->bit_index);
+ unsigned long flags;
+ unsigned int i;
+ u32 value;
+
+ spin_lock_irqsave(&group->lock, flags);
+
+ value = clk_readl(group->smstpcr);
+ if (enable)
+ value &= ~bitmask;
+ else
+ value |= bitmask;
+ clk_writel(value, group->smstpcr);
+
+ spin_unlock_irqrestore(&group->lock, flags);
+
+ if (!enable || !group->mstpsr)
+ return 0;
+
+ for (i = 1000; i > 0; --i) {
+ if (!(clk_readl(group->mstpsr) & bitmask))
+ break;
+ cpu_relax();
+ }
+
+ if (!i) {
+ pr_err("%s: failed to enable %p[%d]\n", __func__,
+ group->smstpcr, clock->bit_index);
+ return -ETIMEDOUT;
+ }
+
+ return 0;
+}
+
+static int cpg_mstp_clock_enable(struct clk_hw *hw)
+{
+ return cpg_mstp_clock_endisable(hw, true);
+}
+
+static void cpg_mstp_clock_disable(struct clk_hw *hw)
+{
+ cpg_mstp_clock_endisable(hw, false);
+}
+
+static int cpg_mstp_clock_is_enabled(struct clk_hw *hw)
+{
+ struct mstp_clock *clock = to_mstp_clock(hw);
+ struct mstp_clock_group *group = clock->group;
+ u32 value;
+
+ if (group->mstpsr)
+ value = clk_readl(group->mstpsr);
+ else
+ value = clk_readl(group->smstpcr);
+
+ return !!(value & BIT(clock->bit_index));
+}
+
+static const struct clk_ops cpg_mstp_clock_ops = {
+ .enable = cpg_mstp_clock_enable,
+ .disable = cpg_mstp_clock_disable,
+ .is_enabled = cpg_mstp_clock_is_enabled,
+};
+
+static struct clk * __init
+cpg_mstp_clock_register(const char *name, const char *parent_name,
+ unsigned int index, struct mstp_clock_group *group)
+{
+ struct clk_init_data init;
+ struct mstp_clock *clock;
+ struct clk *clk;
+
+ clock = kzalloc(sizeof(*clock), GFP_KERNEL);
+ if (!clock) {
+ pr_err("%s: failed to allocate MSTP clock.\n", __func__);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ init.name = name;
+ init.ops = &cpg_mstp_clock_ops;
+ init.flags = CLK_IS_BASIC;
+ init.parent_names = &parent_name;
+ init.num_parents = 1;
+
+ clock->bit_index = index;
+ clock->group = group;
+ clock->hw.init = &init;
+
+ clk = clk_register(NULL, &clock->hw);
+
+ if (IS_ERR(clk))
+ kfree(clock);
+
+ return clk;
+}
+
+static void __init cpg_mstp_clocks_init(struct device_node *np)
+{
+ struct mstp_clock_group *group;
+ struct clk **clks;
+ unsigned int i;
+
+ group = kzalloc(sizeof(*group), GFP_KERNEL);
+ clks = kzalloc(MSTP_MAX_CLOCKS * sizeof(*clks), GFP_KERNEL);
+ if (group == NULL || clks == NULL) {
+ kfree(group);
+ kfree(clks);
+ pr_err("%s: failed to allocate group\n", __func__);
+ return;
+ }
+
+ spin_lock_init(&group->lock);
+ group->data.clks = clks;
+
+ group->smstpcr = of_iomap(np, 0);
+ group->mstpsr = of_iomap(np, 1);
+
+ if (group->smstpcr == NULL) {
+ pr_err("%s: failed to remap SMSTPCR\n", __func__);
+ kfree(group);
+ kfree(clks);
+ return;
+ }
+
+ for (i = 0; i < MSTP_MAX_CLOCKS; ++i) {
+ const char *parent_name;
+ const char *name;
+ u32 clkidx;
+ int ret;
+
+ /* Skip clocks with no name. */
+ ret = of_property_read_string_index(np, "clock-output-names",
+ i, &name);
+ if (ret < 0 || strlen(name) == 0)
+ continue;
+
+ parent_name = of_clk_get_parent_name(np, i);
+ ret = of_property_read_u32_index(np, "renesas,clock-indices", i,
+ &clkidx);
+ if (parent_name == NULL || ret < 0)
+ break;
+
+ if (clkidx >= MSTP_MAX_CLOCKS) {
+ pr_err("%s: invalid clock %s %s index %u)\n",
+ __func__, np->name, name, clkidx);
+ continue;
+ }
+
+ clks[clkidx] = cpg_mstp_clock_register(name, parent_name, i,
+ group);
+ if (!IS_ERR(clks[clkidx])) {
+ group->data.clk_num = max(group->data.clk_num, clkidx);
+ /*
+ * Register a clkdev to let board code retrieve the
+ * clock by name and register aliases for non-DT
+ * devices.
+ *
+ * FIXME: Remove this when all devices that require a
+ * clock will be instantiated from DT.
+ */
+ clk_register_clkdev(clks[clkidx], name, NULL);
+ } else {
+ pr_err("%s: failed to register %s %s clock (%ld)\n",
+ __func__, np->name, name, PTR_ERR(clks[clkidx]));
+ }
+ }
+
+ of_clk_add_provider(np, of_clk_src_onecell_get, &group->data);
+}
+CLK_OF_DECLARE(cpg_mstp_clks, "renesas,cpg-mstp-clocks", cpg_mstp_clocks_init);