add at24 driver

hc

2023-11-06 15ade055295d13f95d49e3d99b09f3bbfb4a43e7

 kernel/arch/arm/mm/highmem.c
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@@ -34,6 +34,11 @@
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 	return *ptep;
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 }
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+static unsigned int fixmap_idx(int type)
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+{
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+	return FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
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+}
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+
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 void *kmap(struct page *page)
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 {
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 	might_sleep();
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@@ -54,12 +59,13 @@
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 void *kmap_atomic(struct page *page)
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 {
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+	pte_t pte = mk_pte(page, kmap_prot);
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 	unsigned int idx;
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 	unsigned long vaddr;
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 	void *kmap;
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 	int type;
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-	preempt_disable();
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+	preempt_disable_nort();
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 	pagefault_disable();
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 	if (!PageHighMem(page))
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 		return page_address(page);
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@@ -79,7 +85,7 @@
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 	type = kmap_atomic_idx_push();
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-	idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
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+	idx = fixmap_idx(type);
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 	vaddr = __fix_to_virt(idx);
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 #ifdef CONFIG_DEBUG_HIGHMEM
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 	/*
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@@ -93,7 +99,10 @@
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 	 * in place, so the contained TLB flush ensures the TLB is updated
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 	 * with the new mapping.
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 	 */
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-	set_fixmap_pte(idx, mk_pte(page, kmap_prot));
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+	current->kmap_pte[type] = pte;
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+#endif
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+	set_fixmap_pte(idx, pte);
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 	return (void *)vaddr;
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 }
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@@ -106,44 +115,75 @@
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 	if (kvaddr >= (void *)FIXADDR_START) {
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 		type = kmap_atomic_idx();
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-		idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
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+		idx = fixmap_idx(type);
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 		if (cache_is_vivt())
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 			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+		current->kmap_pte[type] = __pte(0);
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+#endif
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 #ifdef CONFIG_DEBUG_HIGHMEM
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 		BUG_ON(vaddr != __fix_to_virt(idx));
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-		set_fixmap_pte(idx, __pte(0));
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 #else
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 		(void) idx;  /* to kill a warning */
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 #endif
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+		set_fixmap_pte(idx, __pte(0));
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 		kmap_atomic_idx_pop();
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 	} else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
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 		/* this address was obtained through kmap_high_get() */
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 		kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
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 	}
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 	pagefault_enable();
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-	preempt_enable();
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+	preempt_enable_nort();
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 }
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 EXPORT_SYMBOL(__kunmap_atomic);
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 void *kmap_atomic_pfn(unsigned long pfn)
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 {
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+	pte_t pte = pfn_pte(pfn, kmap_prot);
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 	unsigned long vaddr;
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 	int idx, type;
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 	struct page *page = pfn_to_page(pfn);
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-	preempt_disable();
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+	preempt_disable_nort();
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 	pagefault_disable();
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 	if (!PageHighMem(page))
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 		return page_address(page);
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 	type = kmap_atomic_idx_push();
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-	idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
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+	idx = fixmap_idx(type);
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 	vaddr = __fix_to_virt(idx);
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 #ifdef CONFIG_DEBUG_HIGHMEM
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 	BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
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 #endif
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-	set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+	current->kmap_pte[type] = pte;
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+#endif
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+	set_fixmap_pte(idx, pte);
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 	return (void *)vaddr;
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 }
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+#if defined CONFIG_PREEMPT_RT_FULL
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+void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
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+{
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+	int i;
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+
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+	/*
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+	 * Clear @prev's kmap_atomic mappings
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+	 */
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+	for (i = 0; i < prev_p->kmap_idx; i++) {
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+		int idx = fixmap_idx(i);
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+
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+		set_fixmap_pte(idx, __pte(0));
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+	}
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+	/*
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+	 * Restore @next_p's kmap_atomic mappings
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+	 */
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+	for (i = 0; i < next_p->kmap_idx; i++) {
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+		int idx = fixmap_idx(i);
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+
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+		if (!pte_none(next_p->kmap_pte[i]))
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+			set_fixmap_pte(idx, next_p->kmap_pte[i]);
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+	}
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+}
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+#endif