From 22447a99c97e353bde8f90c2353873f27681d57c Mon Sep 17 00:00:00 2001 From: Pawel Czarnecki Date: Tue, 13 Oct 2020 16:45:52 +0200 Subject: drivers/soc/litex: add LiteX SoC Controller driver This commit adds driver for the FPGA-based LiteX SoC Controller from LiteX SoC builder. Co-developed-by: Mateusz Holenko Signed-off-by: Mateusz Holenko Signed-off-by: Pawel Czarnecki Signed-off-by: Stafford Horne --- drivers/soc/litex/Kconfig | 19 ++++ drivers/soc/litex/Makefile | 3 + drivers/soc/litex/litex_soc_ctrl.c | 176 +++++++++++++++++++++++++++++++++++++ 3 files changed, 198 insertions(+) create mode 100644 drivers/soc/litex/Kconfig create mode 100644 drivers/soc/litex/Makefile create mode 100644 drivers/soc/litex/litex_soc_ctrl.c (limited to 'drivers/soc/litex') diff --git a/drivers/soc/litex/Kconfig b/drivers/soc/litex/Kconfig new file mode 100644 index 000000000000..7c6b009b6f6c --- /dev/null +++ b/drivers/soc/litex/Kconfig @@ -0,0 +1,19 @@ +# SPDX-License_Identifier: GPL-2.0 + +menu "Enable LiteX SoC Builder specific drivers" + +config LITEX + bool + +config LITEX_SOC_CONTROLLER + tristate "Enable LiteX SoC Controller driver" + depends on OF || COMPILE_TEST + select LITEX + help + This option enables the SoC Controller Driver which verifies + LiteX CSR access and provides common litex_get_reg/litex_set_reg + accessors. + All drivers that use functions from litex.h must depend on + LITEX. + +endmenu diff --git a/drivers/soc/litex/Makefile b/drivers/soc/litex/Makefile new file mode 100644 index 000000000000..98ff7325b1c0 --- /dev/null +++ b/drivers/soc/litex/Makefile @@ -0,0 +1,3 @@ +# SPDX-License_Identifier: GPL-2.0 + +obj-$(CONFIG_LITEX_SOC_CONTROLLER) += litex_soc_ctrl.o diff --git a/drivers/soc/litex/litex_soc_ctrl.c b/drivers/soc/litex/litex_soc_ctrl.c new file mode 100644 index 000000000000..1217cafdfd4d --- /dev/null +++ b/drivers/soc/litex/litex_soc_ctrl.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * LiteX SoC Controller Driver + * + * Copyright (C) 2020 Antmicro + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * LiteX SoC Generator, depending on the configuration, can split a single + * logical CSR (Control&Status Register) into a series of consecutive physical + * registers. + * + * For example, in the configuration with 8-bit CSR Bus, 32-bit aligned (the + * default one for 32-bit CPUs) a 32-bit logical CSR will be generated as four + * 32-bit physical registers, each one containing one byte of meaningful data. + * + * For details see: https://github.com/enjoy-digital/litex/wiki/CSR-Bus + * + * 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. + */ + +/** + * litex_set_reg() - Writes the 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 + * + * In the currently supported LiteX configuration (8-bit CSR Bus, 32-bit aligned), + * a 32-bit LiteX CSR is generated as 4 consecutive 32-bit physical registers, + * each one containing one byte of meaningful data. + * + * This function splits a single possibly multi-byte write into a series of + * single-byte writes with a proper offset. + */ +void litex_set_reg(void __iomem *reg, unsigned long reg_size, + unsigned long val) +{ + unsigned long shifted_data, shift, i; + + for (i = 0; i < reg_size; ++i) { + shift = ((reg_size - i - 1) * LITEX_SUBREG_SIZE_BIT); + shifted_data = val >> shift; + + WRITE_LITEX_SUBREGISTER(shifted_data, reg, i); + } +} +EXPORT_SYMBOL_GPL(litex_set_reg); + +/** + * litex_get_reg() - Reads the 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 + * + * Return: Value read from the CSR + * + * In the currently supported LiteX configuration (8-bit CSR Bus, 32-bit aligned), + * a 32-bit LiteX CSR is generated as 4 consecutive 32-bit physical registers, + * each one containing one byte of meaningful data. + * + * This function generates a series of single-byte reads with a proper offset + * and joins their results into a single multi-byte value. + */ +unsigned long litex_get_reg(void __iomem *reg, unsigned long reg_size) +{ + unsigned long shifted_data, shift, i; + unsigned long result = 0; + + for (i = 0; i < reg_size; ++i) { + shifted_data = READ_LITEX_SUBREGISTER(reg, i); + + shift = ((reg_size - i - 1) * LITEX_SUBREG_SIZE_BIT); + result |= (shifted_data << shift); + } + + return result; +} +EXPORT_SYMBOL_GPL(litex_get_reg); + +#define SCRATCH_REG_OFF 0x04 +#define SCRATCH_REG_VALUE 0x12345678 +#define SCRATCH_TEST_VALUE 0xdeadbeef + +/* + * Check LiteX CSR read/write access + * + * This function reads and writes a scratch register in order to verify if CSR + * access works. + * + * In case any problems are detected, the driver should panic. + * + * Access to the LiteX CSR is, by design, done in CPU native endianness. + * The driver should not dynamically configure access functions when + * the endianness mismatch is detected. Such situation indicates problems in + * the soft SoC design and should be solved at the LiteX generator level, + * not in the software. + */ +static int litex_check_csr_access(void __iomem *reg_addr) +{ + unsigned long reg; + + reg = litex_read32(reg_addr + SCRATCH_REG_OFF); + + if (reg != SCRATCH_REG_VALUE) { + panic("Scratch register read error - the system is probably broken! Expected: 0x%x but got: 0x%lx", + SCRATCH_REG_VALUE, reg); + return -EINVAL; + } + + litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_TEST_VALUE); + reg = litex_read32(reg_addr + SCRATCH_REG_OFF); + + if (reg != SCRATCH_TEST_VALUE) { + panic("Scratch register write error - the system is probably broken! Expected: 0x%x but got: 0x%lx", + SCRATCH_TEST_VALUE, reg); + return -EINVAL; + } + + /* restore original value of the SCRATCH register */ + litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_REG_VALUE); + + pr_info("LiteX SoC Controller driver initialized"); + + return 0; +} + +struct litex_soc_ctrl_device { + void __iomem *base; +}; + +static const struct of_device_id litex_soc_ctrl_of_match[] = { + {.compatible = "litex,soc-controller"}, + {}, +}; + +MODULE_DEVICE_TABLE(of, litex_soc_ctrl_of_match); + +static int litex_soc_ctrl_probe(struct platform_device *pdev) +{ + struct litex_soc_ctrl_device *soc_ctrl_dev; + + soc_ctrl_dev = devm_kzalloc(&pdev->dev, sizeof(*soc_ctrl_dev), GFP_KERNEL); + if (!soc_ctrl_dev) + return -ENOMEM; + + soc_ctrl_dev->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(soc_ctrl_dev->base)) + return PTR_ERR(soc_ctrl_dev->base); + + return litex_check_csr_access(soc_ctrl_dev->base); +} + +static struct platform_driver litex_soc_ctrl_driver = { + .driver = { + .name = "litex-soc-controller", + .of_match_table = of_match_ptr(litex_soc_ctrl_of_match) + }, + .probe = litex_soc_ctrl_probe, +}; + +module_platform_driver(litex_soc_ctrl_driver); +MODULE_DESCRIPTION("LiteX SoC Controller driver"); +MODULE_AUTHOR("Antmicro "); +MODULE_LICENSE("GPL v2"); -- cgit v1.2.3