From mboxrd@z Thu Jan 1 00:00:00 1970 From: lorenzo.pieralisi@arm.com (Lorenzo Pieralisi) Date: Thu, 14 Jul 2016 14:42:52 +0100 Subject: [PATCH v7 7/9] acpi/arm64: Add memory-mapped timer support in GTDT driver In-Reply-To: <1468432402-4872-8-git-send-email-fu.wei@linaro.org> References: <1468432402-4872-1-git-send-email-fu.wei@linaro.org> <1468432402-4872-8-git-send-email-fu.wei@linaro.org> Message-ID: <20160714134251.GA30657@red-moon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Jul 14, 2016 at 01:53:20AM +0800, fu.wei at linaro.org wrote: > From: Fu Wei > > This driver adds support for parsing memory-mapped timer in GTDT: > provide a kernel APIs to parse GT Block Structure in GTDT, > export all the info by filling the struct which provided > by parameter(pointer of the struct). > > By this driver, we can add ACPI support for memory-mapped timer in > arm_arch_timer drivers, and separate the ACPI GTDT knowledge from it. > > Signed-off-by: Fu Wei > Signed-off-by: Hanjun Guo > --- > drivers/acpi/arm64/acpi_gtdt.c | 90 ++++++++++++++++++++++++++++++++++++ > include/clocksource/arm_arch_timer.h | 15 ++++++ > include/linux/acpi.h | 1 + > 3 files changed, 106 insertions(+) > > diff --git a/drivers/acpi/arm64/acpi_gtdt.c b/drivers/acpi/arm64/acpi_gtdt.c > index 9ee977d..ff62953 100644 > --- a/drivers/acpi/arm64/acpi_gtdt.c > +++ b/drivers/acpi/arm64/acpi_gtdt.c > @@ -168,3 +168,93 @@ int __init gtdt_arch_timer_init(struct acpi_table_header *table) > > return -EINVAL; > } > + > +/* > + * Helper function for getting the pointer of a timer frame in GT block. > + */ > +static void __init *gtdt_gt_timer_frame(struct acpi_gtdt_timer_block *gt_block, > + int index) > +{ > + void *timer_frame = (void *)gt_block + gt_block->timer_offset + > + sizeof(struct acpi_gtdt_timer_entry) * index; > + > + if (timer_frame <= (void *)gt_block + gt_block->header.length - > + sizeof(struct acpi_gtdt_timer_entry)) > + return timer_frame; Nit: gt_block is an array, right ? I think it would be much simpler if you treat is as such, so that indexing into it would be done automatically by the compiler. Actually, I do not even think you would need this function at all if you treat gt_block as an array, the length check could be done in gtdt_parse_gt_block() straight away. > + > + return NULL; > +} > + > +static int __init gtdt_parse_gt_block(void *platform_timer, int index, > + void *data) > +{ > + struct acpi_gtdt_timer_block *block; > + struct acpi_gtdt_timer_entry *frame; > + struct gt_block_data *block_data; > + int i, j; > + > + if (!platform_timer || !data) > + return -EINVAL; > + > + block = platform_timer; > + block_data = data + sizeof(struct gt_block_data) * index; Nit: See above, data is a struct gt_block_data[] right ? These void pointers parameters are not really great, the caller context knows what they are and it can pass them as pointer to typed array elements anyway unless I am missing something. > + if (!block->block_address || !block->timer_count) { > + pr_err(FW_BUG "invalid GT Block data.\n"); > + return -EINVAL; > + } > + block_data->cntctlbase_phy = (phys_addr_t)block->block_address; > + block_data->timer_count = block->timer_count; > + > + /* > + * Get the GT timer Frame data for every GT Block Timer > + */ > + for (i = 0, j = 0; i < block->timer_count; i++) { What's j needed for (ie can't you use just i instead ?) ? > + frame = gtdt_gt_timer_frame(block, i); > + if (!frame || !frame->base_address || !frame->timer_interrupt) { > + pr_err(FW_BUG "invalid GT Block Timer data.\n"); > + return -EINVAL; > + } > + block_data->timer[j].frame_nr = frame->frame_number; > + block_data->timer[j].cntbase_phy = frame->base_address; > + block_data->timer[j].irq = map_generic_timer_interrupt( > + frame->timer_interrupt, > + frame->timer_flags); > + if (frame->virtual_timer_interrupt) > + block_data->timer[j].virt_irq = > + map_generic_timer_interrupt( > + frame->virtual_timer_interrupt, > + frame->virtual_timer_flags); > + j++; > + } > + > + if (j) > + return 0; > + > + block_data->cntctlbase_phy = (phys_addr_t)NULL; This is wrong. NULL is not meant to be used as a physical address, you must not do that. Is not zeroeing timer_count enough ? I have to understand why you need this because casting NULL into it is not safe, at all. > + block_data->timer_count = 0; > + > + return -EINVAL; > +} > + > +/* > + * Get the GT block info for memory-mapped timer from GTDT table. > + * Please make sure we have called gtdt_arch_timer_init, because it helps to > + * init the global variables. It is a helper function that you call once at boot, you easily determine when it is called, it is not meant to be used in different contexts from different subsystems; I think that this comment is not clear so either you make it clearer or you remove it. > + */ > +int __init gtdt_arch_timer_mem_init(struct gt_block_data *data) > +{ > + void *platform_timer; > + int index = 0; > + > + for_each_platform_timer(platform_timer) { > + if (is_timer_block(platform_timer) && > + !gtdt_parse_gt_block(platform_timer, index, data)) Passing around these opaque void* is a tad ugly, see my comments above about this. Apart from the NULL pointer assignment, everything else is just code clean-up. Thanks, Lorenzo > + index++; > + } > + > + if (index) > + pr_info("found %d memory-mapped timer block.\n", index); > + > + return index; > +} > diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h > index 16dcd10..ece6b3b 100644 > --- a/include/clocksource/arm_arch_timer.h > +++ b/include/clocksource/arm_arch_timer.h > @@ -56,6 +56,8 @@ enum spi_nr { > #define ARCH_TIMER_MEM_PHYS_ACCESS 2 > #define ARCH_TIMER_MEM_VIRT_ACCESS 3 > > +#define ARCH_TIMER_MEM_MAX_FRAME 8 > + > #define ARCH_TIMER_USR_PCT_ACCESS_EN (1 << 0) /* physical counter */ > #define ARCH_TIMER_USR_VCT_ACCESS_EN (1 << 1) /* virtual counter */ > #define ARCH_TIMER_VIRT_EVT_EN (1 << 2) > @@ -71,6 +73,19 @@ struct arch_timer_kvm_info { > int virtual_irq; > }; > > +struct gt_timer_data { > + int frame_nr; > + phys_addr_t cntbase_phy; > + int irq; > + int virt_irq; > +}; > + > +struct gt_block_data { > + phys_addr_t cntctlbase_phy; > + int timer_count; > + struct gt_timer_data timer[ARCH_TIMER_MEM_MAX_FRAME]; > +}; > + > #ifdef CONFIG_ARM_ARCH_TIMER > > extern u32 arch_timer_get_rate(void); > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index 8439579..b1cacbc 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -536,6 +536,7 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *); > int __init gtdt_arch_timer_init(struct acpi_table_header *table); > int __init acpi_gtdt_map_ppi(int type); > int __init acpi_gtdt_c3stop(void); > +int __init gtdt_arch_timer_mem_init(struct gt_block_data *data); > #endif > > #else /* !CONFIG_ACPI */ > -- > 2.5.5 >