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[108.39.255.32]) by smtp.gmail.com with ESMTPSA id i3sm16658957qkd.119.2020.12.28.04.51.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Dec 2020 04:51:17 -0800 (PST) Date: Mon, 28 Dec 2020 07:51:14 -0500 From: "Gabriel L. Somlo" To: shorne@gmail.com, mholenko@antmicro.com, kgugala@antmicro.com Cc: linux-kernel@vger.kernel.org, pczarnecki@internships.antmicro.com, f.kermarrec@gmail.com, gregkh@linuxfoundation.org Subject: Re: [PATCH v5 4/4] drivers/soc/litex: make 'litex_[set|get]_reg()' methods private Message-ID: <20201228125114.GI6062@errol.ini.cmu.edu> References: <20201227161320.2194830-1-gsomlo@gmail.com> <20201227161320.2194830-5-gsomlo@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201227161320.2194830-5-gsomlo@gmail.com> X-Clacks-Overhead: GNU Terry Pratchett Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 27, 2020 at 11:13:20AM -0500, Gabriel Somlo wrote: > The 'litex_[set|get]_reg()' methods use the 'reg_size' parameter to > specify the width of the LiteX CSR (MMIO) register being accessed. > > Since 'u64' is the widest data being supported, the value of 'reg_size' > MUST be between 1 and sizeof(u64), which SHOULD be checked at runtime > if these methods are publicly available for use by other LiteX device > drivers. > > At the same time, none of the existing (or foreseeable) LiteX device > drivers have a need to access registers whose size is unknown during > compilation. As such, all LiteX device drivers should use fixed-width > accessor methods such as 'litex_[write|read][8|16|32|64]()'. > > This patch renames 'litex_[set|get]_reg()' to '_litex_[set|get]_reg()', > indicating that they should NOT be directly called from outside of > the 'include/linux/litex.h' header file. > > Signed-off-by: Gabriel Somlo > --- > drivers/soc/litex/Kconfig | 2 +- > include/linux/litex.h | 35 ++++++++++++++++++++--------------- > 2 files changed, 21 insertions(+), 16 deletions(-) > > diff --git a/drivers/soc/litex/Kconfig b/drivers/soc/litex/Kconfig > index 973f8d2fe1a7..b9b3d51ea7df 100644 > --- a/drivers/soc/litex/Kconfig > +++ b/drivers/soc/litex/Kconfig > @@ -11,7 +11,7 @@ config LITEX_SOC_CONTROLLER > select LITEX > help > This option enables the SoC Controller Driver which verifies > - LiteX CSR access and provides common litex_get_reg/litex_set_reg > + LiteX CSR access and provides common litex_[read|write]* > accessors. > All drivers that use functions from litex.h must depend on > LITEX. > diff --git a/include/linux/litex.h b/include/linux/litex.h > index 3456d527f644..14748fa86a99 100644 > --- a/include/linux/litex.h > +++ b/include/linux/litex.h > @@ -59,21 +59,25 @@ static inline u32 _read_litex_subregister(void __iomem *addr) > ((off) + _litex_num_subregs(size) * LITEX_SUBREG_ALIGN) > > /* > - * The purpose of `litex_set_reg`/`litex_get_reg` is to implement the logic > - * of writing to/reading from the LiteX CSR in a single place that can be > - * then reused by all LiteX drivers. > + * The purpose of `_litex_[set|get]_reg()` is to implement the logic of > + * writing to/reading from the LiteX CSR in a single place that can be then > + * reused by all LiteX drivers via the `litex_[write|read][8|16|32|64]()` > + * accessors for the appropriate data width. > + * NOTE: direct use of `_litex_[set|get]_reg()` by LiteX drivers is strongly > + * discouraged, as they perform no error checking on the requested data width! > */ > > /** > - * litex_set_reg() - Writes the value to the LiteX CSR (Control&Status Register) > + * _litex_set_reg() - Writes a value to the LiteX CSR (Control&Status Register) > * @reg: Address of the CSR > * @reg_size: The width of the CSR expressed in the number of bytes > * @val: Value to be written to the CSR > * > * This function splits a single (possibly multi-byte) LiteX CSR write into > * a series of subregister writes with a proper offset. > + * NOTE: caller is responsible for ensuring (0 < reg_size < sizeof(u64)). This will be fixed in v6 to read "(0 < reg_size <= sizeof(u64))". > */ > -static inline void litex_set_reg(void __iomem *reg, size_t reg_size, u64 val) > +static inline void _litex_set_reg(void __iomem *reg, size_t reg_size, u64 val) > { > u8 shift = _litex_num_subregs(reg_size) * LITEX_SUBREG_SIZE_BIT; > > @@ -85,7 +89,7 @@ static inline void litex_set_reg(void __iomem *reg, size_t reg_size, u64 val) > } > > /** > - * litex_get_reg() - Reads the value of the LiteX CSR (Control&Status Register) > + * _litex_get_reg() - Reads a value of the LiteX CSR (Control&Status Register) > * @reg: Address of the CSR > * @reg_size: The width of the CSR expressed in the number of bytes > * > @@ -93,8 +97,9 @@ static inline void litex_set_reg(void __iomem *reg, size_t reg_size, u64 val) > * > * This function generates a series of subregister reads with a proper offset > * and joins their results into a single (possibly multi-byte) LiteX CSR value. > + * NOTE: caller is responsible for ensuring (0 < reg_size < sizeof(u64)). Ditto. Thanks, --Gabriel > */ > -static inline u64 litex_get_reg(void __iomem *reg, size_t reg_size) > +static inline u64 _litex_get_reg(void __iomem *reg, size_t reg_size) > { > u64 r; > u8 i; > @@ -110,42 +115,42 @@ static inline u64 litex_get_reg(void __iomem *reg, size_t reg_size) > > static inline void litex_write8(void __iomem *reg, u8 val) > { > - litex_set_reg(reg, sizeof(u8), val); > + _litex_set_reg(reg, sizeof(u8), val); > } > > static inline void litex_write16(void __iomem *reg, u16 val) > { > - litex_set_reg(reg, sizeof(u16), val); > + _litex_set_reg(reg, sizeof(u16), val); > } > > static inline void litex_write32(void __iomem *reg, u32 val) > { > - litex_set_reg(reg, sizeof(u32), val); > + _litex_set_reg(reg, sizeof(u32), val); > } > > static inline void litex_write64(void __iomem *reg, u64 val) > { > - litex_set_reg(reg, sizeof(u64), val); > + _litex_set_reg(reg, sizeof(u64), val); > } > > static inline u8 litex_read8(void __iomem *reg) > { > - return litex_get_reg(reg, sizeof(u8)); > + return _litex_get_reg(reg, sizeof(u8)); > } > > static inline u16 litex_read16(void __iomem *reg) > { > - return litex_get_reg(reg, sizeof(u16)); > + return _litex_get_reg(reg, sizeof(u16)); > } > > static inline u32 litex_read32(void __iomem *reg) > { > - return litex_get_reg(reg, sizeof(u32)); > + return _litex_get_reg(reg, sizeof(u32)); > } > > static inline u64 litex_read64(void __iomem *reg) > { > - return litex_get_reg(reg, sizeof(u64)); > + return _litex_get_reg(reg, sizeof(u64)); > } > > #endif /* _LINUX_LITEX_H */ > -- > 2.26.2 >