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[70.228.75.190]) by smtp.gmail.com with ESMTPSA id m15sm7661069qkp.76.2021.12.24.13.16.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Dec 2021 13:16:46 -0800 (PST) From: Atish Patra X-Google-Original-From: Atish Patra To: linux-kernel@vger.kernel.org Cc: Atish Patra , Albert Ou , Atish Patra , Anup Patel , Damien Le Moal , devicetree@vger.kernel.org, Jisheng Zhang , Krzysztof Kozlowski , linux-riscv@lists.infradead.org, Palmer Dabbelt , Paul Walmsley , Rob Herring Subject: [PATCH v1 1/2] RISC-V: Provide a framework for parsing multi-letter ISA extensions Date: Fri, 24 Dec 2021 13:16:31 -0800 Message-Id: <20211224211632.1698523-2-atishp@rivosinc.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211224211632.1698523-1-atishp@rivosinc.com> References: <20211224211632.1698523-1-atishp@rivosinc.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Recently, there were 15 specifications/40 ISA extensions were ratified. Except hypervisor ('H') extension, all of them are multi-letter extensions. Going forward, there will be more number of multi-letter extensions as well. Parsing all of these extensions from ISA string is not scalable. Thus, this patch provides a DT based framework to for easy parsing and querying of any ISA extensions. It facilitates custom user visible strings for the ISA extensions via /proc/cpuinfo as well. Currently, there are no platforms with heterogeneous Linux capable harts. That's why, this patch supports only a single DT node which can only work for systems with homogeneous harts. To support heterogeneous systems, this cpu node must be a subnode for each cpu. Signed-off-by: Atish Patra --- arch/riscv/include/asm/hwcap.h | 31 ++++++++++++++++++ arch/riscv/kernel/cpu.c | 16 ++++++++++ arch/riscv/kernel/cpufeature.c | 58 +++++++++++++++++++++++++++++++++- 3 files changed, 104 insertions(+), 1 deletion(-) diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h index 5ce50468aff1..368ab0f330c8 100644 --- a/arch/riscv/include/asm/hwcap.h +++ b/arch/riscv/include/asm/hwcap.h @@ -34,7 +34,36 @@ extern unsigned long elf_hwcap; #define RISCV_ISA_EXT_s ('s' - 'a') #define RISCV_ISA_EXT_u ('u' - 'a') +/* + * Increse this to higher value as kernel support more ISA extensions. + */ #define RISCV_ISA_EXT_MAX 64 +#define RISCV_ISA_EXT_NAME_LEN_MAX 32 +/* The base ID for multi-letter ISA extensions */ +#define RISCV_ISA_EXT_BASE 26 + +/* + * This enum represent the logical ID for each multi-letter RISC-V ISA extension. + * The logical ID should start from RISCV_ISA_EXT_BASE and must not exceed + * RISCV_ISA_EXT_MAX. 0-25 range is reserved for single letter + * extensions while all the multi-letter extensions should define the next + * available logical extension id. + */ +enum riscv_isa_ext_id { + RISCV_ISA_EXT_ID_MAX = RISCV_ISA_EXT_MAX, +}; + +struct riscv_isa_ext_data { + struct list_head node; + /* Name of the extension property in DT */ + char dtprop[RISCV_ISA_EXT_NAME_LEN_MAX]; + /* Name of the extension displayed to userspace via /proc/cpuinfo */ + char uprop[RISCV_ISA_EXT_NAME_LEN_MAX]; + /* The logical ISA extension ID */ + unsigned int isa_ext_id; +}; + +extern struct list_head riscv_isa_ext_list; unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap); @@ -44,6 +73,8 @@ bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit); #define riscv_isa_extension_available(isa_bitmap, ext) \ __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext) +int riscv_isa_ext_list_add(struct riscv_isa_ext_data *edata); + #endif #endif /* _ASM_RISCV_HWCAP_H */ diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c index f13b2c9ea912..dad95bdd3cca 100644 --- a/arch/riscv/kernel/cpu.c +++ b/arch/riscv/kernel/cpu.c @@ -71,6 +71,21 @@ static void print_isa(struct seq_file *f, const char *isa) seq_puts(f, "\n"); } +static void print_isa_ext(struct seq_file *f) +{ + struct riscv_isa_ext_data *edata; + int count = 0; + + seq_puts(f, "isa-ext\t\t: "); + list_for_each_entry(edata, &riscv_isa_ext_list, node) { + if (count) + seq_puts(f, ","); + seq_write(f, edata->uprop, strnlen(edata->uprop, RISCV_ISA_EXT_NAME_LEN_MAX)); + count++; + } + seq_puts(f, "\n"); +} + static void print_mmu(struct seq_file *f, const char *mmu_type) { #if defined(CONFIG_32BIT) @@ -113,6 +128,7 @@ static int c_show(struct seq_file *m, void *v) seq_printf(m, "hart\t\t: %lu\n", cpuid_to_hartid_map(cpu_id)); if (!of_property_read_string(node, "riscv,isa", &isa)) print_isa(m, isa); + print_isa_ext(m); if (!of_property_read_string(node, "mmu-type", &mmu)) print_mmu(m, mmu); if (!of_property_read_string(node, "compatible", &compat) diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index d959d207a40d..c70eeec17f5b 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -7,6 +7,8 @@ */ #include +#include +#include #include #include #include @@ -18,6 +20,8 @@ unsigned long elf_hwcap __read_mostly; /* Host ISA bitmap */ static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly; +LIST_HEAD(riscv_isa_ext_list); + #ifdef CONFIG_FPU __ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_fpu); #endif @@ -59,12 +63,60 @@ bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit) } EXPORT_SYMBOL_GPL(__riscv_isa_extension_available); +#define __RISCV_ISA_EXT_DATA(DTPROP, UPROP, EXTID) \ + { \ + .dtprop = #DTPROP, \ + .uprop = #UPROP, \ + .isa_ext_id = EXTID, \ + } + +static struct riscv_isa_ext_data isa_ext_arr[] = { + __RISCV_ISA_EXT_DATA("", "", RISCV_ISA_EXT_MAX), +}; + +int riscv_isa_ext_list_add(struct riscv_isa_ext_data *edata) +{ + struct device_node *node, *enode; + int eid; + + if (!edata || !edata->dtprop) + return -EINVAL; + + node = of_find_node_by_path("/cpus"); + if (!node) { + pr_err("No CPU information found in DT\n"); + return -ENOENT; + } + + enode = of_get_child_by_name(node, "riscv,isa-ext"); + if (!enode) { + pr_err("No riscv-isa-ext found in DT\n"); + return -ENOENT; + } + + eid = edata->isa_ext_id; + if (eid < RISCV_ISA_EXT_BASE || eid >= RISCV_ISA_EXT_MAX) + return -EINVAL; + + if (!of_property_read_bool(enode, edata->dtprop)) { + pr_err("The ISA extension %s is not present in DT\n", edata->dtprop); + return -ENODEV; + } + + /* Enable the extension id in the riscv_isa for easier probing */ + riscv_isa[0] |= 1 << eid; + list_add(&edata->node, &riscv_isa_ext_list); + pr_info("RISC-V ISA extension '%s' available\n", edata->uprop); + + return 0; +} + void __init riscv_fill_hwcap(void) { struct device_node *node; const char *isa; char print_str[BITS_PER_LONG + 1]; - size_t i, j, isa_len; + size_t i, j, isa_len, ext_arr_sz; static unsigned long isa2hwcap[256] = {0}; isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I; @@ -148,4 +200,8 @@ void __init riscv_fill_hwcap(void) if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D)) static_branch_enable(&cpu_hwcap_fpu); #endif + + ext_arr_sz = ARRAY_SIZE(isa_ext_arr); + for (i = 0; i < ext_arr_sz - 1; i++) + riscv_isa_ext_list_add(&isa_ext_arr[i]); } -- 2.33.1