mips: bmips: rework and cache CBR addr handling

Rework the handling of the CBR address and cache it. This address
doesn't change and can be cached instead of reading the register every
time.

This is in preparation of permitting to tweak the CBR address in DT with
broken SoC or bootloader.

bmips_cbr_addr is defined in setup.c for each arch to keep compatibility
with legacy brcm47xx/brcm63xx and generic BMIPS target.

Acked-by: Florian Fainelli <[e-mail]>
Signed-off-by: Christian Marangi <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/bcm47xx/prom.c

···
 #include <linux/ssb/ssb_driver_chipcommon.h>
 #include <linux/ssb/ssb_regs.h>
 #include <linux/smp.h>
+#include <asm/bmips.h>
 #include <asm/bootinfo.h>
 #include <bcm47xx.h>
 #include <bcm47xx_board.h>
···
 
 void __init prom_init(void)
 {
+	/* Cache CBR addr before CPU/DMA setup */
+	bmips_cbr_addr = BMIPS_GET_CBR();
 	prom_init_mem();
 	setup_8250_early_printk_port(CKSEG1ADDR(BCM47XX_SERIAL_ADDR), 0, 0);
 }

arch/mips/bcm47xx/setup.c

···
 #include <linux/ssb/ssb.h>
 #include <linux/ssb/ssb_embedded.h>
 #include <linux/bcma/bcma_soc.h>
+#include <asm/bmips.h>
 #include <asm/bootinfo.h>
 #include <asm/idle.h>
 #include <asm/prom.h>
···
 #include <asm/time.h>
 #include <bcm47xx.h>
 #include <bcm47xx_board.h>
+
+/* CBR addr doesn't change and we can cache it */
+void __iomem *bmips_cbr_addr __read_mostly;
 
 union bcm47xx_bus bcm47xx_bus;
 EXPORT_SYMBOL(bcm47xx_bus);

arch/mips/bcm63xx/prom.c

···
 {
 	u32 reg, mask;
 
+	/* Cache CBR addr before CPU/DMA setup */
+	bmips_cbr_addr = BMIPS_GET_CBR();
+
 	bcm63xx_cpu_init();
 
 	/* stop any running watchdog */

arch/mips/bcm63xx/setup.c

···
 #include <linux/memblock.h>
 #include <linux/ioport.h>
 #include <linux/pm.h>
+#include <asm/bmips.h>
 #include <asm/bootinfo.h>
 #include <asm/time.h>
 #include <asm/reboot.h>
···
 #include <bcm63xx_regs.h>
 #include <bcm63xx_io.h>
 #include <bcm63xx_gpio.h>
+
+/* CBR addr doesn't change and we can cache it */
+void __iomem *bmips_cbr_addr __read_mostly;
 
 void bcm63xx_machine_halt(void)
 {

arch/mips/bmips/dma.c

···
 
 void arch_sync_dma_for_cpu_all(void)
 {
-	void __iomem *cbr = BMIPS_GET_CBR();
+	void __iomem *cbr = bmips_cbr_addr;
 	u32 cfg;
 
 	if (boot_cpu_type() != CPU_BMIPS3300 &&

arch/mips/bmips/setup.c

···
 #define REG_BCM6328_OTP		((void __iomem *)CKSEG1ADDR(0x1000062c))
 #define BCM6328_TP1_DISABLED	BIT(9)
 
+/* CBR addr doesn't change and we can cache it */
+void __iomem *bmips_cbr_addr __read_mostly;
+
 extern bool bmips_rac_flush_disable;
 
 static const unsigned long kbase = VMLINUX_LOAD_ADDRESS & 0xfff00000;
···
 	 * because the bootloader is not initializing it properly.
 	 */
 	bmips_rac_flush_disable = !!(read_c0_brcm_cmt_local() & (1 << 31)) ||
-				  !!BMIPS_GET_CBR();
+				  !!bmips_cbr_addr;
 }
 
 static void bcm6368_quirks(void)
···
 
 void __init prom_init(void)
 {
+	/* Cache CBR addr before CPU/DMA setup */
+	bmips_cbr_addr = BMIPS_GET_CBR();
 	bmips_init_cfe();
 	bmips_cpu_setup();
 	register_bmips_smp_ops();

arch/mips/include/asm/bmips.h

···
 extern char bmips_smp_int_vec[];
 extern char bmips_smp_int_vec_end[];
 
+extern void __iomem *bmips_cbr_addr;
 extern int bmips_smp_enabled;
 extern int bmips_cpu_offset;
 extern cpumask_t bmips_booted_mask;

arch/mips/kernel/smp-bmips.c

···
 		info.val = val;
 		bmips_set_reset_vec_remote(&info);
 	} else {
-		void __iomem *cbr = BMIPS_GET_CBR();
+		void __iomem *cbr = bmips_cbr_addr;
 
 		if (cpu == 0)
 			__raw_writel(val, cbr + BMIPS_RELO_VECTOR_CONTROL_0);
···
 
 void bmips_cpu_setup(void)
 {
-	void __iomem __maybe_unused *cbr = BMIPS_GET_CBR();
+	void __iomem __maybe_unused *cbr = bmips_cbr_addr;
 	u32 __maybe_unused cfg;
 
 	switch (current_cpu_type()) {