[PATCH v3 3/8] clk: shmobile: Add MSTP clock support
Laurent Pinchart
laurent.pinchart+renesas at ideasonboard.com
Tue Nov 19 09:45:42 EST 2013
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.
Cc: devicetree at vger.kernel.org
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
---
.../bindings/clock/renesas,cpg-mstp-clocks.txt | 48 +++++
drivers/clk/shmobile/Makefile | 1 +
drivers/clk/shmobile/clk-mstp.c | 229 +++++++++++++++++++++
3 files changed, 278 insertions(+)
create mode 100644 Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt
create mode 100644 drivers/clk/shmobile/clk-mstp.c
diff --git a/Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt b/Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt
new file mode 100644
index 0000000..126b17e
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/renesas,cpg-mstp-clocks.txt
@@ -0,0 +1,48 @@
+* Renesas CPG Module Stop (MSTP) Clocks
+
+The CPG can gate SoC device clocks. The gates are organized in groups of up to
+32 gates.
+
+This device tree binding describes a single 32 gate clocks group per node.
+Clocks are referenced by user nodes by the MSTP node phandle and the clock
+index in the group, from 0 to 31.
+
+Required Properties:
+
+ - compatible: Must be one of the following
+ - "renesas,r8a7790-mstp-clocks" for R8A7790 (R-Car H2) MSTP gate clocks
+ - "renesas,r8a7791-mstp-clocks" for R8A7791 (R-Car M2) MSTP gate clocks
+ - "renesas,cpg-mstp-clock" for generic MSTP gate clocks
+ - reg: Base address and length of the memory resource used by the MSTP
+ clocks
+ - clocks: Reference to the parent clocks
+ - #clock-cells: Must be 1
+ - clock-output-names: The name of the clocks as free-form strings
+ - renesas,indices: Indices of the gate clocks into the group (0 to 31)
+
+The clocks, clock-output-names and renesas,indices properties contain one
+entry per gate clock. The MSTP groups are sparsely populated. Unimplemented
+gate clocks must not be declared.
+
+
+Example
+-------
+
+ #include <dt-bindings/clock/r8a7790-clock.h>
+
+ mstp3_clks: mstp3_clks at e615013c {
+ compatible = "renesas,r8a7790-mstp-clocks", "renesas,cpg-mstp-clocks";
+ reg = <0 0xe615013c 0 4>, <0 0xe6150048 0 4>;
+ clocks = <&cp_clk>, <&mmc1_clk>, <&sd3_clk>, <&sd2_clk>,
+ <&cpg_clocks R8A7790_CLK_SD1>, <&cpg_clocks R8A7790_CLK_SD0>,
+ <&mmc0_clk>;
+ #clock-cells = <1>;
+ clock-output-names =
+ "tpu0", "mmcif1", "sdhi3", "sdhi2",
+ "sdhi1", "sdhi0", "mmcif0";
+ renesas,clock-indices = <
+ R8A7790_CLK_TPU0 R8A7790_CLK_MMCIF1 R8A7790_CLK_SDHI3
+ R8A7790_CLK_SDHI2 R8A7790_CLK_SDHI1 R8A7790_CLK_SDHI0
+ R8A7790_CLK_MMCIF0
+ >;
+ };
diff --git a/drivers/clk/shmobile/Makefile b/drivers/clk/shmobile/Makefile
index eded163..4df35a0 100644
--- a/drivers/clk/shmobile/Makefile
+++ b/drivers/clk/shmobile/Makefile
@@ -2,6 +2,7 @@ obj-$(CONFIG_ARCH_EMEV2) += clk-emev2.o
obj-$(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 0000000..e576b60
--- /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 at 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);
--
1.8.3.2
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