[PATCH v5] clk: sunxi: Add Allwinner A20/A31 GMAC clock unit

[Chen-Yu Tsai]

The Allwinner A20/A31 clock module controls the transmit clock source
and interface type of the GMAC ethernet controller. Model this as
a single clock for GMAC drivers to use.

Signed-off-by: Chen-Yu Tsai <wens at csie.org>
---

Hi,

This is v5 of the Allwinner A20 GMAC clock patch. Hans noted a
compiler warning: unused variable in the previous version.
The DT bits remain the same, and Maxime has already taken them.

The Allwinner A20 SoC integrates an early version of dwmac
IP from Synopsys. On top of that is a hardware glue layer.
This layer needs to be configured before the dwmac can be
used.

Part of the glue layer is a clock mux, which controls the
source and direction of the TX clock used by GMAC.

Changes since v4:

  * Removed unused variable in GMAC clock driver left over from v3

Changes since v3:

  * Rework error checking in GMAC clock driver
  * Clarify required parent clock order for GMAC clock in DT bindings
  * Rewrite commit log for "ARM: dts: sun7i: Add ethernet alias for GMAC"
  * Corrected "a20-olinuxino-micro" in commit message
  * Rewrite comments in sun7i dtsi to clarify purpose of dummy clocks
  * Rebase onto Maxime's sunxi-next branch

Changes since v2:

  * Added more comments on GMAC clock driver
  * Drop CLK_SET_PARENT_GATE in GMAC clock driver
  * Use macro for max clock parents
  * Line wrapping

Changes since v1:

  * Added optional reset control to stmmac driver core
  * Added non CONFIG_RESET_CONROLLER routines for the above change
  * Extended callback API, as discussed with Srinivas
  * Used new stmmac_of_data to pass features and callbacks,
    instead of platform data, as discussed
  * Seperated clock module glue layer into clock driver


Cheers
ChenYu

---
 Documentation/devicetree/bindings/clock/sunxi.txt | 30 +++++++
 drivers/clk/sunxi/clk-sunxi.c                     | 96 +++++++++++++++++++++++
 2 files changed, 126 insertions(+)

diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
index 0cf679b..28421d2 100644
--- a/Documentation/devicetree/bindings/clock/sunxi.txt
+++ b/Documentation/devicetree/bindings/clock/sunxi.txt
@@ -37,6 +37,7 @@ Required properties:
 	"allwinner,sun6i-a31-apb2-gates-clk" - for the APB2 gates on A31
 	"allwinner,sun4i-mod0-clk" - for the module 0 family of clocks
 	"allwinner,sun7i-a20-out-clk" - for the external output clocks
+	"allwinner,sun7i-a20-gmac-clk" - for the GMAC clock module on A20/A31
 
 Required properties for all clocks:
 - reg : shall be the control register address for the clock.
@@ -50,6 +51,9 @@ Required properties for all clocks:
 	If the clock module only has one output, the name shall be the
 	module name.
 
+For "allwinner,sun7i-a20-gmac-clk", the parent clocks shall be fixed rate
+dummy clocks at 25 MHz and 125 MHz, respectively. See example.
+
 Clock consumers should specify the desired clocks they use with a
 "clocks" phandle cell. Consumers that are using a gated clock should
 provide an additional ID in their clock property. This ID is the
@@ -96,3 +100,29 @@ mmc0_clk: clk at 01c20088 {
 	clocks = <&osc24M>, <&pll6 1>, <&pll5 1>;
 	clock-output-names = "mmc0";
 };
+
+mii_phy_tx_clk: clk at 2 {
+	#clock-cells = <0>;
+	compatible = "fixed-clock";
+	clock-frequency = <25000000>;
+	clock-output-names = "mii_phy_tx";
+};
+
+gmac_int_tx_clk: clk at 3 {
+	#clock-cells = <0>;
+	compatible = "fixed-clock";
+	clock-frequency = <125000000>;
+	clock-output-names = "gmac_int_tx";
+};
+
+gmac_clk: clk at 01c20164 {
+	#clock-cells = <0>;
+	compatible = "allwinner,sun7i-a20-gmac-clk";
+	reg = <0x01c20164 0x4>;
+	/*
+	 * The first clock must be fixed at 25MHz;
+	 * the second clock must be fixed at 125MHz
+	 */
+	clocks = <&mii_phy_tx_clk>, <&gmac_int_tx_clk>;
+	clock-output-names = "gmac";
+};
diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
index 736fb60..54a5d55 100644
--- a/drivers/clk/sunxi/clk-sunxi.c
+++ b/drivers/clk/sunxi/clk-sunxi.c
@@ -379,6 +379,102 @@ static void sun7i_a20_get_out_factors(u32 *freq, u32 parent_rate,
 
 
 /**
+ * sun7i_a20_gmac_clk_setup - Setup function for A20/A31 GMAC clock module
+ *
+ * This clock looks something like this
+ *                               ________________________
+ *  MII TX clock from PHY >-----|___________    _________|----> to GMAC core
+ *  GMAC Int. RGMII TX clk >----|___________\__/__gate---|----> to PHY
+ *  Ext. 125MHz RGMII TX clk >--|__divider__/            |
+ *                              |________________________|
+ *
+ * The external 125 MHz reference is optional, i.e. GMAC can use its
+ * internal TX clock just fine. The A31 GMAC clock module does not have
+ * the divider controls for the external reference.
+ *
+ * To keep it simple, let the GMAC use either the MII TX clock for MII mode,
+ * and its internal TX clock for GMII and RGMII modes. The GMAC driver should
+ * select the appropriate source and gate/ungate the output to the PHY.
+ *
+ * Only the GMAC should use this clock. Altering the clock so that it doesn't
+ * match the GMAC's operation parameters will result in the GMAC not being
+ * able to send traffic out. The GMAC driver should set the clock rate and
+ * enable/disable this clock to configure the required state. The clock
+ * driver then responds by auto-reparenting the clock.
+ */
+
+#define SUN7I_A20_GMAC_GPIT	2
+#define SUN7I_A20_GMAC_MASK	0x3
+#define SUN7I_A20_GMAC_PARENTS	2
+
+static void __init sun7i_a20_gmac_clk_setup(struct device_node *node)
+{
+	struct clk *clk;
+	struct clk_mux *mux;
+	struct clk_gate *gate;
+	const char *clk_name = node->name;
+	const char *parents[SUN7I_A20_GMAC_PARENTS];
+	void *reg;
+
+	if (of_property_read_string(node, "clock-output-names", &clk_name))
+		return;
+
+	/* allocate mux and gate clock structs */
+	mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL);
+	if (!mux)
+		return;
+
+	gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
+	if (!gate)
+		goto free_mux;
+
+	/* gmac clock requires exactly 2 parents */
+	parents[0] = of_clk_get_parent_name(node, 0);
+	parents[1] = of_clk_get_parent_name(node, 1);
+	if (!parents[0] || !parents[1])
+		goto free_gate;
+
+	reg = of_iomap(node, 0);
+	if (!reg)
+		goto free_gate;
+
+	/* set up gate and fixed rate properties */
+	gate->reg = reg;
+	gate->bit_idx = SUN7I_A20_GMAC_GPIT;
+	gate->lock = &clk_lock;
+	mux->reg = reg;
+	mux->mask = SUN7I_A20_GMAC_MASK;
+	mux->flags = CLK_MUX_INDEX_BIT;
+	mux->lock = &clk_lock;
+
+	clk = clk_register_composite(NULL, clk_name,
+			parents, SUN7I_A20_GMAC_PARENTS,
+			&mux->hw, &clk_mux_ops,
+			NULL, NULL,
+			&gate->hw, &clk_gate_ops,
+			0);
+
+	if (IS_ERR(clk))
+		goto iounmap_reg;
+
+	of_clk_add_provider(node, of_clk_src_simple_get, clk);
+	clk_register_clkdev(clk, clk_name, NULL);
+
+	return;
+
+iounmap_reg:
+	iounmap(reg);
+free_gate:
+	kfree(gate);
+free_mux:
+	kfree(mux);
+}
+CLK_OF_DECLARE(sun7i_a20_gmac, "allwinner,sun7i-a20-gmac-clk",
+		sun7i_a20_gmac_clk_setup);
+
+
+
+/**
  * sunxi_factors_clk_setup() - Setup function for factor clocks
  */
 
-- 
1.9.0.rc3