ARC: allow userspace DSP applications to use AGU extensions

To be able to run DSP-enabled userspace applications with AGU
(address generation unit) extensions we additionally need to
save and restore following registers at context switch:
* AGU_AP*
* AGU_OS*
* AGU_MOD*

Reviewed-by: Vineet Gupta <[e-mail]>
Signed-off-by: Eugeniy Paltsev <[e-mail]>
Signed-off-by: Vineet Gupta <[e-mail]>

arch/arc/Kconfig

···
 	help
 	  DSP extension presence in HW, support save / restore DSP registers to
 	  run DSP-enabled userspace applications
+
+config ARC_DSP_AGU_USERSPACE
+	bool "Support DSP with AGU for userspace apps"
+	select ARC_HAS_ACCL_REGS
+	select ARC_DSP_HANDLED
+	select ARC_DSP_SAVE_RESTORE_REGS
+	help
+	  DSP and AGU extensions presence in HW, support save / restore DSP
+	  and AGU registers to run DSP-enabled userspace applications
 endchoice
 
 config ARC_IRQ_NO_AUTOSAVE

arch/arc/include/asm/arcregs.h

···
 #define ARC_AUX_DSP_CTRL	0x59F
 #define ARC_AUX_DSP_FFT_CTRL	0x59E
 
+#define ARC_AUX_AGU_BUILD	0xCC
+#define ARC_AUX_AGU_AP0		0x5C0
+#define ARC_AUX_AGU_AP1		0x5C1
+#define ARC_AUX_AGU_AP2		0x5C2
+#define ARC_AUX_AGU_AP3		0x5C3
+#define ARC_AUX_AGU_OS0		0x5D0
+#define ARC_AUX_AGU_OS1		0x5D1
+#define ARC_AUX_AGU_MOD0	0x5E0
+#define ARC_AUX_AGU_MOD1	0x5E1
+#define ARC_AUX_AGU_MOD2	0x5E2
+#define ARC_AUX_AGU_MOD3	0x5E3
+
 #ifndef __ASSEMBLY__
 
 #include <soc/arc/aux.h>

arch/arc/include/asm/asserts.h

···
 /* Helpers to sanitize config options. */
 
 void chk_opt_strict(char *opt_name, bool hw_exists, bool opt_ena);
+void chk_opt_weak(char *opt_name, bool hw_exists, bool opt_ena);
 
 /*
  * Check required config option:
···
 #define CHK_OPT_STRICT(opt_name, hw_exists)				\
 ({									\
 	chk_opt_strict(#opt_name, hw_exists, IS_ENABLED(opt_name));	\
+})
+
+/*
+ * Check optional config option:
+ *  - panic in case of OPT enabled but corresponding HW absent.
+*/
+#define CHK_OPT_WEAK(opt_name, hw_exists)				\
+({									\
+	chk_opt_weak(#opt_name, hw_exists, IS_ENABLED(opt_name));	\
 })
 
 #endif /* __ASM_ARC_ASSERTS_H */

arch/arc/include/asm/dsp-impl.h

···
 
 	DSP_AUX_SAVE_RESTORE(saveto, readfrom, DSP_BFLY0);
 	DSP_AUX_SAVE_RESTORE(saveto, readfrom, DSP_FFT_CTRL);
+
+#ifdef CONFIG_ARC_DSP_AGU_USERSPACE
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_AP0);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_AP1);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_AP2);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_AP3);
+
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_OS0);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_OS1);
+
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_MOD0);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_MOD1);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_MOD2);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_MOD3);
+#endif /* CONFIG_ARC_DSP_AGU_USERSPACE */
 }
 
 #else /* !CONFIG_ARC_DSP_SAVE_RESTORE_REGS */
···
 	return !!bcr.ver;
 }
 
+static inline bool agu_exist(void)
+{
+	struct bcr_generic bcr;
+
+	READ_BCR(ARC_AUX_AGU_BUILD, bcr);
+	return !!bcr.ver;
+}
+
 static inline void dsp_config_check(void)
 {
 	CHK_OPT_STRICT(CONFIG_ARC_DSP_HANDLED, dsp_exist());
+	CHK_OPT_WEAK(CONFIG_ARC_DSP_AGU_USERSPACE, agu_exist());
 }
 
 #endif /* __ASEMBLY__ */

arch/arc/include/asm/dsp.h

···
  */
 struct dsp_callee_regs {
 	unsigned long ACC0_GLO, ACC0_GHI, DSP_BFLY0, DSP_FFT_CTRL;
+#ifdef CONFIG_ARC_DSP_AGU_USERSPACE
+	unsigned long AGU_AP0, AGU_AP1, AGU_AP2, AGU_AP3;
+	unsigned long AGU_OS0, AGU_OS1;
+	unsigned long AGU_MOD0, AGU_MOD1, AGU_MOD2, AGU_MOD3;
+#endif
 };
 
 #endif /* !__ASSEMBLY__ */

arch/arc/kernel/setup.c

···
 		panic("Disable %s, hardware NOT present\n", opt_name);
 }
 
+void chk_opt_weak(char *opt_name, bool hw_exists, bool opt_ena)
+{
+	if (!hw_exists && opt_ena)
+		panic("Disable %s, hardware NOT present\n", opt_name);
+}
+
 static void arc_chk_core_config(void)
 {
 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];