powerpc/85xx: use the BRx registers to enable indirect mode on the P1022DS

In order to enable the DIU video controller on the P1022DS, the FPGA needs
to be switched to "indirect mode", where the localbus is disabled and
the FPGA is accessed via writes to localbus chip select signals CS0 and CS1.

To obtain the address of CS0 and CS1, the platform driver uses an "indirect
pixis mode" device tree node.  This node assumes that the localbus 'ranges'
property is sorted in chip-select order.  That is, reg value 0 maps to
CS0, reg value 1 maps to CS1, etc.  This is how the 'ranges' property is
supposed to be arranged.

Unfortunately, the 'ranges' property is often mis-arranged, and not just on
the P1022DS.  Linux normally does not care, since it does not program the
localbus.  But the indirect-mode code on the P1022DS does care.

The "proper" fix is to have U-Boot fix the 'ranges' property, but this would
be too cumbersome.  The names and 'reg' properties of all the localbus
devices would also need to be updated, and determining which localbus device
maps to which chip select is board-specific.

Instead, we determine the CS0/CS1 base addresses the same way that U-boot
does -- by reading the BRx registers directly and mapping them to physical
addresses.  This code is simpler and more reliable, and it does not require
a U-boot or device tree change.

Since the indirect pixis device tree node is no longer needed, the node is
deleted from the DTS.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/boot/dts/p1022ds.dtsi

@@ -33,22 +33,6 @@
  */
 
 &board_lbc {
-	/*
-	 * This node is used to access the pixis via "indirect" mode,
-	 * which is done by writing the pixis register index to chip
-	 * select 0 and the value to/from chip select 1.  Indirect
-	 * mode is the only way to access the pixis when DIU video
-	 * is enabled.  Note that this assumes that the first column
-	 * of the 'ranges' property above is the chip select number.
-	 */
-	board-control@0,0 {
-		compatible = "fsl,p1022ds-indirect-pixis";
-		reg = <0x0 0x0 1	/* CS0 */
-		       0x1 0x0 1>;	/* CS1 */
-		interrupt-parent = <&mpic>;
-		interrupts = <8 0 0 0>;
-	};
-
 	nor@0,0 {
 		#address-cells = <1>;
 		#size-cells = <1>;

arch/powerpc/platforms/85xx/p1022_ds.c

@@ -27,6 +27,7 @@
 #include <sysdev/fsl_pci.h>
 #include <asm/udbg.h>
 #include <asm/fsl_guts.h>
+#include <asm/fsl_lbc.h>
 #include "smp.h"
 
 #include "mpc85xx.h"
@@ -142,17 +143,73 @@ static void p1022ds_set_gamma_table(enum fsl_diu_monitor_port port,
 {
 }
 
+struct fsl_law {
+	u32	lawbar;
+	u32	reserved1;
+	u32	lawar;
+	u32	reserved[5];
+};
+
+#define LAWBAR_MASK	0x00F00000
+#define LAWBAR_SHIFT	12
+
+#define LAWAR_EN	0x80000000
+#define LAWAR_TGT_MASK	0x01F00000
+#define LAW_TRGT_IF_LBC	(0x04 << 20)
+
+#define LAWAR_MASK	(LAWAR_EN | LAWAR_TGT_MASK)
+#define LAWAR_MATCH	(LAWAR_EN | LAW_TRGT_IF_LBC)
+
+#define BR_BA		0xFFFF8000
+
+/*
+ * Map a BRx value to a physical address
+ *
+ * The localbus BRx registers only store the lower 32 bits of the address.  To
+ * obtain the upper four bits, we need to scan the LAW table.  The entry which
+ * maps to the localbus will contain the upper four bits.
+ */
+static phys_addr_t lbc_br_to_phys(const void *ecm, unsigned int count, u32 br)
+{
+#ifndef CONFIG_PHYS_64BIT
+	/*
+	 * If we only have 32-bit addressing, then the BRx address *is* the
+	 * physical address.
+	 */
+	return br & BR_BA;
+#else
+	const struct fsl_law *law = ecm + 0xc08;
+	unsigned int i;
+
+	for (i = 0; i < count; i++) {
+		u64 lawbar = in_be32(&law[i].lawbar);
+		u32 lawar = in_be32(&law[i].lawar);
+
+		if ((lawar & LAWAR_MASK) == LAWAR_MATCH)
+			/* Extract the upper four bits */
+			return (br & BR_BA) | ((lawbar & LAWBAR_MASK) << 12);
+	}
+
+	return 0;
+#endif
+}
+
 /**
  * p1022ds_set_monitor_port: switch the output to a different monitor port
- *
  */
 static void p1022ds_set_monitor_port(enum fsl_diu_monitor_port port)
 {
 	struct device_node *guts_node;
-	struct device_node *indirect_node = NULL;
+	struct device_node *lbc_node = NULL;
+	struct device_node *law_node = NULL;
 	struct ccsr_guts __iomem *guts;
+	struct fsl_lbc_regs *lbc = NULL;
+	void *ecm = NULL;
 	u8 __iomem *lbc_lcs0_ba = NULL;
 	u8 __iomem *lbc_lcs1_ba = NULL;
+	phys_addr_t cs0_addr, cs1_addr;
+	const __be32 *iprop;
+	unsigned int num_laws;
 	u8 b;
 
 	/* Map the global utilities registers. */
@@ -168,25 +225,43 @@ static void p1022ds_set_monitor_port(enum fsl_diu_monitor_port port)
 		goto exit;
 	}
 
-	indirect_node = of_find_compatible_node(NULL, NULL,
-					     "fsl,p1022ds-indirect-pixis");
-	if (!indirect_node) {
-		pr_err("p1022ds: missing pixis indirect mode node\n");
+	lbc_node = of_find_compatible_node(NULL, NULL, "fsl,p1022-elbc");
+	if (!lbc_node) {
+		pr_err("p1022ds: missing localbus node\n");
 		goto exit;
 	}
 
-	lbc_lcs0_ba = of_iomap(indirect_node, 0);
-	if (!lbc_lcs0_ba) {
-		pr_err("p1022ds: could not map localbus chip select 0\n");
+	lbc = of_iomap(lbc_node, 0);
+	if (!lbc) {
+		pr_err("p1022ds: could not map localbus node\n");
 		goto exit;
 	}
 
-	lbc_lcs1_ba = of_iomap(indirect_node, 1);
-	if (!lbc_lcs1_ba) {
-		pr_err("p1022ds: could not map localbus chip select 1\n");
+	law_node = of_find_compatible_node(NULL, NULL, "fsl,ecm-law");
+	if (!law_node) {
+		pr_err("p1022ds: missing local access window node\n");
 		goto exit;
 	}
 
+	ecm = of_iomap(law_node, 0);
+	if (!ecm) {
+		pr_err("p1022ds: could not map local access window node\n");
+		goto exit;
+	}
+
+	iprop = of_get_property(law_node, "fsl,num-laws", 0);
+	if (!iprop) {
+		pr_err("p1022ds: LAW node is missing fsl,num-laws property\n");
+		goto exit;
+	}
+	num_laws = be32_to_cpup(iprop);
+
+	cs0_addr = lbc_br_to_phys(ecm, num_laws, in_be32(&lbc->bank[0].br));
+	cs1_addr = lbc_br_to_phys(ecm, num_laws, in_be32(&lbc->bank[1].br));
+
+	lbc_lcs0_ba = ioremap(cs0_addr, 1);
+	lbc_lcs1_ba = ioremap(cs1_addr, 1);
+
 	/* Make sure we're in indirect mode first. */
 	if ((in_be32(&guts->pmuxcr) & PMUXCR_ELBCDIU_MASK) !=
 	    PMUXCR_ELBCDIU_DIU) {
@@ -254,10 +329,15 @@ exit:
 		iounmap(lbc_lcs1_ba);
 	if (lbc_lcs0_ba)
 		iounmap(lbc_lcs0_ba);
+	if (lbc)
+		iounmap(lbc);
+	if (ecm)
+		iounmap(ecm);
 	if (guts)
 		iounmap(guts);
 
-	of_node_put(indirect_node);
+	of_node_put(law_node);
+	of_node_put(lbc_node);
 	of_node_put(guts_node);
 }