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OSPI Linux driver

OSPI Linux driver

Introduction

The Octal-SPI Flash Controller can be used to provide access to Serial Flash devices. Standard Serial Peripheral Interface (SPI) is supported along with high performance Octal SPI variants. The Octal-SPI Flash Controller transfer the data either in a memory mapped direct fashion or in an indirect fashion where the controller is set up via configuration registers to silently perform some requested operation, signalling its completion via interrupts or status registers. For indirect operations, data is transferred between system memory and external FLASH memory via an internal SRAM. OSPI has it’s own internal DMA which is used to read the data from the flash, SRAM is accessible only in case of DMA mode of operation (indirect mode).

In INDAC (Indirect Access Controller) mode DMA writes are not supported, Non-DMA, DAC or STIG modes are used for flash writes. In INDAC(DMA) mode only flash reads are supported.

Features Supported in HW

  1. Direct mode of memory mapped operation.

  2. Software triggered IO mode (STIG) up to 8-bytes of data transfers.

  3. Indirect DMA reads.

  4. NON-DMA read and write support

  5. Local SRAM to reduce AHB overhead.

  6. Supports SDR and DDR protocols.

  7. Programmable master mode clock frequencies.

  8. Serial clock with programmable polarity.

  9. Programmable peripheral selects (chip select).

  10. Support for Single and Octal instructions.

  11. Interrupts and polled based operations.

Features supported in driver

  1. Software triggered IO mode (STIG) up to 8-bytes of data transfers.

  2. INDAC DMA reads.

  3. SDR and DDR mode support.

  4. Support for Octal mode.

  5. Interrupt based transfers.

  6. RX Tuning support for PHY modes.

  7. NON-DMA read and write support.

Driver Missing features, Known Issues and Limitations

  • STIG Memory Bank.

  • When Micron OSPI flash devices such as MT35XU02G and MT35XU01G, which feature multi-die architecture, are configured to operate in SDR mode, the following warning message—accompanied by a call trace—is observed during Linux boot. This warning does not affect the functionality of the OSPI driver

[ 2.281990] ------------[ cut here ]------------ [ 2.286602] enabling reset hack; may not recover from unexpected reboots [ 2.293307] WARNING: CPU: 7 PID: 100 at drivers/mtd/spi-nor/core.c:3819 spi_nor_set_4byte_addr_mode+0xac/0xb4

Important AR links

  • 2023.1 Versal: OSPI flash probe fails with BSP images on VCK190 in Linux AR Link

Supported Flash parts

  • Micron

  • ISSI

  • Gigadevice

  • Macronix (works only up to 150MHz)

Testing

  • Flashcp

  • mtd utilities.

  • mtd_speedtest

  • mtd_stresstest

  • File System testing - UBIFS and JFFS2

Kernel Configuration

CONFIG_SPI_CADENCE_QUADSPI=y

Device-tree

Sample Device-tree node for OSPI 

spi@f1010000 { compatible = "xlnx,versal-ospi-1.0", "cadence,qspi", "cdns,qspi-nor"; status = "okay"; reg = <0x0 0xf1010000 0x0 0x10000 0x0 0xc0000000 0x0 0x20000000>; interrupts = <0x0 0x7c 0x4 0x0 0x7c 0x4>; clock-names = "ref_clk", "pclk"; cdns,fifo-depth = <0x100>; cdns,fifo-width = <0x4>; cdns,is-dma = <0x1>; cdns,is-stig-pgm = <0x1>; cdns,trigger-address = <0xc0000000>; #stream-id-cells = <0x1>; #address-cells = <0x1>; #size-cells = <0x0>; clocks = <0x3 0x3a 0x3 0x52>; power-domains = <0x7 0x1822402a>; bus-num = <0x2>; num-cs = <0x1>; reset-gpios = <0x28 0xc 0x0>; phandle = <0x33>; flash@0 { compatible = "mt35xu02g", "micron,m25p80", "spi-flash"; reg = <0x0>; #address-cells = <0x1>; #size-cells = <0x1>; cdns,read-delay = <0x0>; cdns,tshsl-ns = <0x0>; cdns,tsd2d-ns = <0x0>; cdns,tchsh-ns = <0x1>; cdns,tslch-ns = <0x1>; spi-tx-bus-width = <0x1>; spi-rx-bus-width = <0x8>; spi-max-frequency = <0x1312d00>; partition@0 { label = "spi0-flash0"; reg = <0x0 0x10000000>; }; }; };

NOTE:

  • If broken-flash-reset is defined in the flash node and spi-max-frequency is less than 50 MHz then the OSPI will operate in SDR-NON-PHY mode.

  • From 2025.2 release kernel if broken-flash-reset is defined in the flash node and spi-max-frequency is greater than equal than 50 MHz then the OSPI will operate in SDR-PHY mode.

  • If broken-flash-reset is NOT defined in the flash node then the OSPI will operate in DDR-PHY mode and irrespective of spi-max-frequency value the OSPI bus frequency will be equal to the OSPI Ref_Clk.

Performance Details

At frequency 200 MHz

DDR mode:

Read Speed: 282560 KiB/s

Write Speed: 1661 KiB/s

Mainline Status

Features added to mainline

  • SDR NON-PHY mode

  • DMA support

  • Flash Device Reset

Not in Mainline

  • DDR mode support

  • Rx tuning

  • Stacked mode support

  • Support for ISSI, Gigadevice and Macronix.

Change Log

2025.2

  • 9e279cd - mtd: spi-nor: Add SDR-PHY support for OSPI flashes

  • 8abcd4c - spi: spi-cadence: Enable SDR-PHY mode when spi-max-frequency is greater than 50 MHz

  • 9e279cd - mtd: spi-nor: Add SDR-PHY support for OSPI flashes

  • 6e3ea32 - mtd: spi-nor: Add die erase support for Micron multi-die OSPI flash

2025.1

  • 4e46a91 - Fix block protection failure on Macronix OSPI flash

  • a1ad524 - Add support for MX66UW2G345GXRI00 OSPI flash

  • 652bcc0 - Fix incorrect die count reported by Gigadevice OSPI flashes

  • cae9073 - Retrieve all chip-select values from the flash node

  • 526f906 - Align Broken STIG quirk implementation with upstream

2024.2

  • 5c46c46 - Add quirk to skip STIG mode for data xfers

2024.1

  • 1c82238 - Store GPIO info for resetting device during resume

  • 42f7d1c - Add support for MX66UM2G45G Macronix flash part

  • 4cce023 - Fix RX tuning failure for OSPI flashes connected in stacked mode

  • 1c6af10 - Disable 16bit SR operation for gd25lx256e flash

  • 016ecd9 - Fix call trace during suspend/resume

  • 0182633 - Remove dependency on SRAM Fill Register during indirect non-dma read

2023.2

  • None

2023.1

  • ae655c5 - Replace all spi->chip_select and spi->cs_gpiod references with function call

  • 8880c61 - Ads stacked memories support as per the new DT bindings

  • adc1e5f - Fix race condition while scheduling periodic tuning

2022.2

  • c59a288 - Add module param to configure read timeout

2022.1

  • 583238d - set cqspi to the driver_data field of struct device

  • ae78bf6 - Fix ospi resume failures

2021.2

  • 7737141 - fix linking failure for ARCH arm

  • 5249597 - Limit RX max tap to 127

2021.1

  • b832b6b - Added support for OSPI Macronix(mx25um51345g) part .

  • 7216a02 - Added support for reading from unaligned address.

  • 5ca8ce8 - Rx periodic tuning updates for Master DLL mode.

2020.2

  • 6ab15b2 - Added support for stacked mode.

  • 3ff8d4e, 46fe093 - Added support for ISSI and GIGADEVICE parts.

  • 56e44ec - Fix the issues in Rx periodic tuning.

2020.1

  • 508f0df, e0d688d - Added support for UBIFS and JFFS2 file system support.

  • 40ede36 - Added support for NON-DMA read and write support.

  • f73c158 - Added support for RX periodic tuning (periodicity of 5 minutes). 

2019.2

  • New driver



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