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([79.115.63.75]) by smtp.gmail.com with ESMTPSA id h21-20020a1709070b1500b00a0180de2797sm941490ejl.74.2023.11.23.08.07.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Nov 2023 08:07:30 -0800 (PST) From: Tudor Ambarus To: pratyush@kernel.org, michael@walle.cc Cc: linux-mtd@lists.infradead.org, linux-doc@vger.kernel.org, corbet@lwn.net, linux-kernel@vger.kernel.org, Tudor Ambarus Subject: [PATCH 2/2] docs: mtd: spi-nor: drop obsolete info Date: Thu, 23 Nov 2023 18:07:21 +0200 Message-Id: <20231123160721.64561-3-tudor.ambarus@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231123160721.64561-1-tudor.ambarus@linaro.org> References: <20231123160721.64561-1-tudor.ambarus@linaro.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3053; i=tudor.ambarus@linaro.org; h=from:subject; bh=25OPubX9uzUyfM/XTP0zGdZT9n+Quh1N4wccoUHj8ic=; b=owEBbQGS/pANAwAKAUtVT0eljRTpAcsmYgBlX3i5QFJr2OKH8EvKa+v/4w+Lmao2JCr0Mw7oV /lLZU7/wzqJATMEAAEKAB0WIQQdQirKzw7IbV4d/t9LVU9HpY0U6QUCZV94uQAKCRBLVU9HpY0U 6QCbCAC4SngJRGZ0qeFbmpZ6hInfmNRUbhAEQHkQxqBDDtkD+zPfaHPtRDnzLTVp4wl9ZW+pv50 Uov8OIk5qS4gbc4Z4bJEqhsWZmOSpEV6Vlb7Se2LnRTeY7q0MPjA+Q4XkScUAnFB0EszN0POp5w 3gfs2paYIdVQbg3Nie3Dxomp8hpxgIjDEsjtP91bvES+Taajqgx4JQvOFebwksgWbrOp7r9iMrX s2wMu7w8QDSh9bODQfv8sDI1E3Ou+DKbos9OBejAD7lFPfLLpRsvZ1bKQSAMA5H/PVXrwOBXlmz CZt0aHdVmp+6qwMi1p03b9uGe7yE2Y3dTr2W9ZurmmhwLp22 X-Developer-Key: i=tudor.ambarus@linaro.org; a=openpgp; fpr=280B06FD4CAAD2980C46DDDF4DB1B079AD29CF3D Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The architecture description is obsolete, it no longer applies to the current SPI NOR framework state, remove it. Signed-off-by: Tudor Ambarus Reviewed-by: Michael Walle Reviewed-by: Pratyush Yadav --- Documentation/driver-api/mtd/spi-nor.rst | 62 ------------------------ 1 file changed, 62 deletions(-) diff --git a/Documentation/driver-api/mtd/spi-nor.rst b/Documentation/drive= r-api/mtd/spi-nor.rst index cc8e81e09544..7a8737fe181d 100644 --- a/Documentation/driver-api/mtd/spi-nor.rst +++ b/Documentation/driver-api/mtd/spi-nor.rst @@ -2,68 +2,6 @@ SPI NOR framework =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 -Part I - Why do we need this framework? ---------------------------------------- - -SPI bus controllers (drivers/spi/) only deal with streams of bytes; the bus -controller operates agnostic of the specific device attached. However, some -controllers (such as Freescale's QuadSPI controller) cannot easily handle -arbitrary streams of bytes, but rather are designed specifically for SPI N= OR. - -In particular, Freescale's QuadSPI controller must know the NOR commands to -find the right LUT sequence. Unfortunately, the SPI subsystem has no notio= n of -opcodes, addresses, or data payloads; a SPI controller simply knows to sen= d or -receive bytes (Tx and Rx). Therefore, we must define a new layering scheme= under -which the controller driver is aware of the opcodes, addressing, and other -details of the SPI NOR protocol. - -Part II - How does the framework work? --------------------------------------- - -This framework just adds a new layer between the MTD and the SPI bus drive= r. -With this new layer, the SPI NOR controller driver does not depend on the -m25p80 code anymore. - -Before this framework, the layer is like:: - - MTD - ------------------------ - m25p80 - ------------------------ - SPI bus driver - ------------------------ - SPI NOR chip - -After this framework, the layer is like:: - - MTD - ------------------------ - SPI NOR framework - ------------------------ - m25p80 - ------------------------ - SPI bus driver - ------------------------ - SPI NOR chip - -With the SPI NOR controller driver (Freescale QuadSPI), it looks like:: - - MTD - ------------------------ - SPI NOR framework - ------------------------ - fsl-quadSPI - ------------------------ - SPI NOR chip - -Part III - How can drivers use the framework? ---------------------------------------------- - -The main API is spi_nor_scan(). Before you call the hook, a driver should -initialize the necessary fields for spi_nor{}. Please see -drivers/mtd/spi-nor/spi-nor.c for detail. Please also refer to spi-fsl-qsp= i.c -when you want to write a new driver for a SPI NOR controller. - How to propose a new flash addition ----------------------------------- =20 --=20 2.34.1