clk: mpc512x: add backwards compat to the CCF code

extend the recently added COMMON_CLK platform support for MPC512x such
that it works with incomplete device tree data which lacks clock specs

Cc: Mike Turquette <mturquette@linaro.org>
Cc: Anatolij Gustschin <agust@denx.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Gerhard Sittig <gsi@denx.de>
[agust@denx.de: moved node macro definitions out of the function body]
Signed-off-by: Anatolij Gustschin <agust@denx.de>

arch/powerpc/platforms/512x/clock-commonclk.c

@@ -11,6 +11,7 @@
  * (at your option) any later version.
  */
 
+#include <linux/bitops.h>
 #include <linux/clk-provider.h>
 #include <linux/clkdev.h>
 #include <linux/device.h>
@@ -737,6 +738,35 @@ static void mpc5121_clk_provide_migration_support(void)
 	clk_prepare_enable(clks[MPC512x_CLK_PCI]);	/* PCI */
 }
 
+/*
+ * those macros are not exactly pretty, but they encapsulate a lot
+ * of copy'n'paste heavy code which is even more ugly, and reduce
+ * the potential for inconsistencies in those many code copies
+ */
+#define FOR_NODES(compatname) \
+	for_each_compatible_node(np, NULL, compatname)
+
+#define NODE_PREP do { \
+	of_address_to_resource(np, 0, &res); \
+	snprintf(devname, sizeof(devname), "%08x.%s", res.start, np->name); \
+} while (0)
+
+#define NODE_CHK(clkname, clkitem, regnode, regflag) do { \
+	struct clk *clk; \
+	clk = of_clk_get_by_name(np, clkname); \
+	if (IS_ERR(clk)) { \
+		clk = clkitem; \
+		clk_register_clkdev(clk, clkname, devname); \
+		if (regnode) \
+			clk_register_clkdev(clk, clkname, np->name); \
+		did_register |= DID_REG_ ## regflag; \
+		pr_debug("clock alias name '%s' for dev '%s' pointer %p\n", \
+			 clkname, devname, clk); \
+	} else { \
+		clk_put(clk); \
+	} \
+} while (0)
+
 /*
  * register source code provided fallback results for clock lookups,
  * these get consulted when OF based clock lookup fails (that is in the
@@ -745,7 +775,147 @@ static void mpc5121_clk_provide_migration_support(void)
  */
 static void mpc5121_clk_provide_backwards_compat(void)
 {
-	/* TODO */
+	enum did_reg_flags {
+		DID_REG_PSC	= BIT(0),
+		DID_REG_PSCFIFO	= BIT(1),
+		DID_REG_NFC	= BIT(2),
+		DID_REG_CAN	= BIT(3),
+		DID_REG_I2C	= BIT(4),
+		DID_REG_DIU	= BIT(5),
+		DID_REG_VIU	= BIT(6),
+		DID_REG_FEC	= BIT(7),
+		DID_REG_USB	= BIT(8),
+		DID_REG_PATA	= BIT(9),
+	};
+
+	int did_register;
+	struct device_node *np;
+	struct resource res;
+	int idx;
+	char devname[32];
+
+	did_register = 0;
+
+	FOR_NODES(mpc512x_select_psc_compat()) {
+		NODE_PREP;
+		idx = (res.start >> 8) & 0xf;
+		NODE_CHK("ipg", clks[MPC512x_CLK_PSC0 + idx], 0, PSC);
+		NODE_CHK("mclk", clks[MPC512x_CLK_PSC0_MCLK + idx], 0, PSC);
+	}
+
+	FOR_NODES("fsl,mpc5121-psc-fifo") {
+		NODE_PREP;
+		NODE_CHK("ipg", clks[MPC512x_CLK_PSC_FIFO], 1, PSCFIFO);
+	}
+
+	FOR_NODES("fsl,mpc5121-nfc") {
+		NODE_PREP;
+		NODE_CHK("ipg", clks[MPC512x_CLK_NFC], 0, NFC);
+	}
+
+	FOR_NODES("fsl,mpc5121-mscan") {
+		NODE_PREP;
+		idx = 0;
+		idx += (res.start & 0x2000) ? 2 : 0;
+		idx += (res.start & 0x0080) ? 1 : 0;
+		NODE_CHK("ipg", clks[MPC512x_CLK_BDLC], 0, CAN);
+		NODE_CHK("mclk", clks[MPC512x_CLK_MSCAN0_MCLK + idx], 0, CAN);
+	}
+
+	/*
+	 * do register the 'ips', 'sys', and 'ref' names globally
+	 * instead of inside each individual CAN node, as there is no
+	 * potential for a name conflict (in contrast to 'ipg' and 'mclk')
+	 */
+	if (did_register & DID_REG_CAN) {
+		clk_register_clkdev(clks[MPC512x_CLK_IPS], "ips", NULL);
+		clk_register_clkdev(clks[MPC512x_CLK_SYS], "sys", NULL);
+		clk_register_clkdev(clks[MPC512x_CLK_REF], "ref", NULL);
+	}
+
+	FOR_NODES("fsl,mpc5121-i2c") {
+		NODE_PREP;
+		NODE_CHK("ipg", clks[MPC512x_CLK_I2C], 0, I2C);
+	}
+
+	/*
+	 * workaround for the fact that the I2C driver does an "anonymous"
+	 * lookup (NULL name spec, which yields the first clock spec) for
+	 * which we cannot register an alias -- a _global_ 'ipg' alias that
+	 * is not bound to any device name and returns the I2C clock item
+	 * is not a good idea
+	 *
+	 * so we have the lookup in the peripheral driver fail, which is
+	 * silent and non-fatal, and pre-enable the clock item here such
+	 * that register access is possible
+	 *
+	 * see commit b3bfce2b "i2c: mpc: cleanup clock API use" for
+	 * details, adjusting s/NULL/"ipg"/ in i2c-mpc.c would make this
+	 * workaround obsolete
+	 */
+	if (did_register & DID_REG_I2C)
+		clk_prepare_enable(clks[MPC512x_CLK_I2C]);
+
+	FOR_NODES("fsl,mpc5121-diu") {
+		NODE_PREP;
+		NODE_CHK("ipg", clks[MPC512x_CLK_DIU], 1, DIU);
+	}
+
+	FOR_NODES("fsl,mpc5121-viu") {
+		NODE_PREP;
+		NODE_CHK("ipg", clks[MPC512x_CLK_VIU], 0, VIU);
+	}
+
+	/*
+	 * note that 2771399a "fs_enet: cleanup clock API use" did use the
+	 * "per" string for the clock lookup in contrast to the "ipg" name
+	 * which most other nodes are using -- this is not a fatal thing
+	 * but just something to keep in mind when doing compatibility
+	 * registration, it's a non-issue with up-to-date device tree data
+	 */
+	FOR_NODES("fsl,mpc5121-fec") {
+		NODE_PREP;
+		NODE_CHK("per", clks[MPC512x_CLK_FEC], 0, FEC);
+	}
+	FOR_NODES("fsl,mpc5121-fec-mdio") {
+		NODE_PREP;
+		NODE_CHK("per", clks[MPC512x_CLK_FEC], 0, FEC);
+	}
+
+	FOR_NODES("fsl,mpc5121-usb2-dr") {
+		NODE_PREP;
+		idx = (res.start & 0x4000) ? 1 : 0;
+		NODE_CHK("ipg", clks[MPC512x_CLK_USB1 + idx], 0, USB);
+	}
+
+	FOR_NODES("fsl,mpc5121-pata") {
+		NODE_PREP;
+		NODE_CHK("ipg", clks[MPC512x_CLK_PATA], 0, PATA);
+	}
+
+	/*
+	 * try to collapse diagnostics into a single line of output yet
+	 * provide a full list of what is missing, to avoid noise in the
+	 * absence of up-to-date device tree data -- backwards
+	 * compatibility to old DTBs is a requirement, updates may be
+	 * desirable or preferrable but are not at all mandatory
+	 */
+	if (did_register) {
+		pr_notice("device tree lacks clock specs, adding fallbacks (0x%x,%s%s%s%s%s%s%s%s%s%s)\n",
+			  did_register,
+			  (did_register & DID_REG_PSC) ? " PSC" : "",
+			  (did_register & DID_REG_PSCFIFO) ? " PSCFIFO" : "",
+			  (did_register & DID_REG_NFC) ? " NFC" : "",
+			  (did_register & DID_REG_CAN) ? " CAN" : "",
+			  (did_register & DID_REG_I2C) ? " I2C" : "",
+			  (did_register & DID_REG_DIU) ? " DIU" : "",
+			  (did_register & DID_REG_VIU) ? " VIU" : "",
+			  (did_register & DID_REG_FEC) ? " FEC" : "",
+			  (did_register & DID_REG_USB) ? " USB" : "",
+			  (did_register & DID_REG_PATA) ? " PATA" : "");
+	} else {
+		pr_debug("device tree has clock specs, no fallbacks added\n");
+	}
 }
 
 int __init mpc5121_clk_init(void)