From 9d93a9e8aab3f82b6742dd034a6a81d4025cd82e Mon Sep 17 00:00:00 2001 From: Gabriel Somlo Date: Tue, 12 Jan 2021 12:31:40 -0500 Subject: drivers/soc/litex: move generic accessors to litex.h Move generic LiteX CSR (MMIO) register accessors to litex.h and declare them as "static inline", in preparation for supporting 32-bit CSR subregisters and 64-bit CPUs. NOTE: this is a non-functional change. Signed-off-by: Gabriel Somlo Signed-off-by: Stafford Horne --- drivers/soc/litex/litex_soc_ctrl.c | 73 -------------------------------------- 1 file changed, 73 deletions(-) (limited to 'drivers/soc/litex') diff --git a/drivers/soc/litex/litex_soc_ctrl.c b/drivers/soc/litex/litex_soc_ctrl.c index 1217cafdfd4d..65977526d68e 100644 --- a/drivers/soc/litex/litex_soc_ctrl.c +++ b/drivers/soc/litex/litex_soc_ctrl.c @@ -16,79 +16,6 @@ #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 -- cgit v1.2.3 From 51f109228308a87c7f2583360e54acfc567203da Mon Sep 17 00:00:00 2001 From: Gabriel Somlo Date: Tue, 12 Jan 2021 12:31:43 -0500 Subject: drivers/soc/litex: support 32-bit subregisters, 64-bit CPUs Upstream LiteX now defaults to using 32-bit CSR subregisters (see https://github.com/enjoy-digital/litex/commit/a2b71fde). This patch expands on commit 22447a99c97e ("drivers/soc/litex: add LiteX SoC Controller driver"), adding support for handling both 8- and 32-bit LiteX CSR (MMIO) subregisters, as determined by the LITEX_SUBREG_SIZE Kconfig option. NOTE that while LITEX_SUBREG_SIZE could theoretically be a device tree property, defining it as a compile-time constant allows for much better optimization of the resulting code. This is further supported by the low expected usefulness of deploying the same kernel across LiteX SoCs built with different CSR-Bus data widths. Finally, the litex_[read|write][8|16|32|64]() accessors are redefined in terms of litex_[get|set]_reg(), which, after compiler optimization, will result in code as efficient as hardcoded shifts, but with the added benefit of automatically matching the appropriate LITEX_SUBREG_SIZE. NOTE that litex_[get|set]_reg() nominally operate on 64-bit data, but that will also be optimized by the compiler in situations where narrower data is used from a call site. Signed-off-by: Gabriel Somlo Signed-off-by: Stafford Horne --- drivers/soc/litex/Kconfig | 12 ++++++++++++ drivers/soc/litex/litex_soc_ctrl.c | 3 ++- 2 files changed, 14 insertions(+), 1 deletion(-) (limited to 'drivers/soc/litex') diff --git a/drivers/soc/litex/Kconfig b/drivers/soc/litex/Kconfig index 7c6b009b6f6c..973f8d2fe1a7 100644 --- a/drivers/soc/litex/Kconfig +++ b/drivers/soc/litex/Kconfig @@ -16,4 +16,16 @@ config LITEX_SOC_CONTROLLER All drivers that use functions from litex.h must depend on LITEX. +config LITEX_SUBREG_SIZE + int "Size of a LiteX CSR subregister, in bytes" + depends on LITEX + range 1 4 + default 4 + help + LiteX MMIO registers (referred to as Configuration and Status + registers, or CSRs) are spread across adjacent 8- or 32-bit + subregisters, located at 32-bit aligned MMIO addresses. Use + this to select the appropriate size (1 or 4 bytes) matching + your particular LiteX build. + endmenu diff --git a/drivers/soc/litex/litex_soc_ctrl.c b/drivers/soc/litex/litex_soc_ctrl.c index 65977526d68e..da17ba56b795 100644 --- a/drivers/soc/litex/litex_soc_ctrl.c +++ b/drivers/soc/litex/litex_soc_ctrl.c @@ -58,7 +58,8 @@ static int litex_check_csr_access(void __iomem *reg_addr) /* restore original value of the SCRATCH register */ litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_REG_VALUE); - pr_info("LiteX SoC Controller driver initialized"); + pr_info("LiteX SoC Controller driver initialized: subreg:%d, align:%d", + LITEX_SUBREG_SIZE, LITEX_SUBREG_ALIGN); return 0; } -- cgit v1.2.3 From 4f70d150294b3ddfbe4be7130ca53898cd5b91be Mon Sep 17 00:00:00 2001 From: Gabriel Somlo Date: Tue, 12 Jan 2021 12:31:44 -0500 Subject: drivers/soc/litex: make 'litex_[set|get]_reg()' methods private 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 Signed-off-by: Stafford Horne --- drivers/soc/litex/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/soc/litex') 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. -- cgit v1.2.3 From 3706f9f76a4f79f8e7b2eb8b99877e89fe9ad732 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Tue, 19 Jan 2021 09:09:38 +0100 Subject: drivers/soc/litex: Add restart handler Let the LiteX SoC Controller register a restart handler, which resets the LiteX SoC by writing 1 to CSR_CTRL_RESET_ADDR. Signed-off-by: Geert Uytterhoeven Reviewed-by: Joel Stanley Signed-off-by: Stafford Horne --- drivers/soc/litex/litex_soc_ctrl.c | 42 +++++++++++++++++++++++++++++++++++++- 1 file changed, 41 insertions(+), 1 deletion(-) (limited to 'drivers/soc/litex') diff --git a/drivers/soc/litex/litex_soc_ctrl.c b/drivers/soc/litex/litex_soc_ctrl.c index da17ba56b795..a7dd5be9fd5b 100644 --- a/drivers/soc/litex/litex_soc_ctrl.c +++ b/drivers/soc/litex/litex_soc_ctrl.c @@ -15,6 +15,11 @@ #include #include #include +#include + +/* reset register located at the base address */ +#define RESET_REG_OFF 0x00 +#define RESET_REG_VALUE 0x00000001 #define SCRATCH_REG_OFF 0x04 #define SCRATCH_REG_VALUE 0x12345678 @@ -66,8 +71,19 @@ static int litex_check_csr_access(void __iomem *reg_addr) struct litex_soc_ctrl_device { void __iomem *base; + struct notifier_block reset_nb; }; +static int litex_reset_handler(struct notifier_block *this, unsigned long mode, + void *cmd) +{ + struct litex_soc_ctrl_device *soc_ctrl_dev = + container_of(this, struct litex_soc_ctrl_device, reset_nb); + + litex_write32(soc_ctrl_dev->base + RESET_REG_OFF, RESET_REG_VALUE); + return NOTIFY_DONE; +} + static const struct of_device_id litex_soc_ctrl_of_match[] = { {.compatible = "litex,soc-controller"}, {}, @@ -78,6 +94,7 @@ 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; + int error; soc_ctrl_dev = devm_kzalloc(&pdev->dev, sizeof(*soc_ctrl_dev), GFP_KERNEL); if (!soc_ctrl_dev) @@ -87,7 +104,29 @@ static int litex_soc_ctrl_probe(struct platform_device *pdev) if (IS_ERR(soc_ctrl_dev->base)) return PTR_ERR(soc_ctrl_dev->base); - return litex_check_csr_access(soc_ctrl_dev->base); + error = litex_check_csr_access(soc_ctrl_dev->base); + if (error) + return error; + + platform_set_drvdata(pdev, soc_ctrl_dev); + + soc_ctrl_dev->reset_nb.notifier_call = litex_reset_handler; + soc_ctrl_dev->reset_nb.priority = 128; + error = register_restart_handler(&soc_ctrl_dev->reset_nb); + if (error) { + dev_warn(&pdev->dev, "cannot register restart handler: %d\n", + error); + } + + return 0; +} + +static int litex_soc_ctrl_remove(struct platform_device *pdev) +{ + struct litex_soc_ctrl_device *soc_ctrl_dev = platform_get_drvdata(pdev); + + unregister_restart_handler(&soc_ctrl_dev->reset_nb); + return 0; } static struct platform_driver litex_soc_ctrl_driver = { @@ -96,6 +135,7 @@ static struct platform_driver litex_soc_ctrl_driver = { .of_match_table = of_match_ptr(litex_soc_ctrl_of_match) }, .probe = litex_soc_ctrl_probe, + .remove = litex_soc_ctrl_remove, }; module_platform_driver(litex_soc_ctrl_driver); -- cgit v1.2.3