| Message ID | 20230127164040.1047583-5-gatien.chevallier@foss.st.com |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce STM32 system bus | expand |
On Fri, 27 Jan 2023 17:40:38 +0100 Gatien Chevallier <gatien.chevallier@foss.st.com> wrote: > This driver is checking the access rights of the different > peripherals connected to the system bus. If access is denied, > the associated device tree node is skipped so the platform bus > does not probe it. > > Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com> > Signed-off-by: Loic PALLARDY <loic.pallardy@st.com> Hi Gatien, A few comments inline, Thanks, Jonathan > diff --git a/drivers/bus/stm32_sys_bus.c b/drivers/bus/stm32_sys_bus.c > new file mode 100644 > index 000000000000..c12926466bae > --- /dev/null > +++ b/drivers/bus/stm32_sys_bus.c > @@ -0,0 +1,168 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2023, STMicroelectronics - All Rights Reserved > + */ > + > +#include <linux/bitfield.h> > +#include <linux/bits.h> > +#include <linux/device.h> > +#include <linux/err.h> > +#include <linux/io.h> > +#include <linux/init.h> > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/of_platform.h> > +#include <linux/platform_device.h> > + > +/* ETZPC peripheral as firewall bus */ > +/* ETZPC registers */ > +#define ETZPC_DECPROT 0x10 > + > +/* ETZPC miscellaneous */ > +#define ETZPC_PROT_MASK GENMASK(1, 0) > +#define ETZPC_PROT_A7NS 0x3 > +#define ETZPC_DECPROT_SHIFT 1 This define makes the code harder to read. What we care about is the number of bits in the register divided by number of entries. (which is 2) hence the shift by 1. See below for more on this. > + > +#define IDS_PER_DECPROT_REGS 16 > +#define STM32MP15_ETZPC_ENTRIES 96 > +#define STM32MP13_ETZPC_ENTRIES 64 These defines just make the code harder to check. They aren't magic numbers, but rather just telling us how many entries there are, so I would just put them in the structures directly. Their use make it clear what they are without needing to give them a name. > +struct stm32_sys_bus_match_data { Comment on naming of this below. > + unsigned int max_entries; > +}; > + +static int stm32_etzpc_get_access(struct sys_bus_data *pdata, struct device_node *np) +{ + int err; + u32 offset, reg_offset, sec_val, id; + + err = stm32_sys_bus_get_periph_id(pdata, np, &id); + if (err) + return err; + + /* Check access configuration, 16 peripherals per register */ + reg_offset = ETZPC_DECPROT + 0x4 * (id / IDS_PER_DECPROT_REGS); + offset = (id % IDS_PER_DECPROT_REGS) << ETZPC_DECPROT_SHIFT; Use of defines in here is actively unhelpful when it comes to review. I would suggest letting the maths be self explanatory (even if it's more code). offset = (id % IDS_PER_DECPROT_REGS) * (sizeof(u32) * BITS_PER_BYTE / IDS_PER_DECPROT_REGS); Or if you prefer have a define of #define DECPROT_BITS_PER_ID (sizeof(u32) * BITS_PER_BYTE / IDS_PER_DECPROT_REGS) and offset = (id % IDS_PER_DECPROT_REGS) * DECPROT_BITS_PER_ID; + + /* Verify peripheral is non-secure and attributed to cortex A7 */ + sec_val = (readl(pdata->sys_bus_base + reg_offset) >> offset) & ETZPC_PROT_MASK; + if (sec_val != ETZPC_PROT_A7NS) { + dev_dbg(pdata->dev, "Invalid bus configuration: reg_offset %#x, value %d\n", + reg_offset, sec_val); + return -EACCES; + } + + return 0; +} + ... > +static int stm32_sys_bus_probe(struct platform_device *pdev) > +{ > + struct sys_bus_data *pdata; > + void __iomem *mmio; > + struct device_node *np = pdev->dev.of_node; I'd be consistent. You use dev_of_node() accessor elsewhere, so should use it here as well. > + > + pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); > + if (!pdata) > + return -ENOMEM; > + > + mmio = devm_platform_ioremap_resource(pdev, 0); > + if (IS_ERR(mmio)) > + return PTR_ERR(mmio); > + > + pdata->sys_bus_base = mmio; > + pdata->pconf = of_device_get_match_data(&pdev->dev); > + pdata->dev = &pdev->dev; > + > + platform_set_drvdata(pdev, pdata); Does this get used? I can't immediately spot where but maybe I just missed it. > + > + stm32_sys_bus_populate(pdata); > + > + /* Populate all available nodes */ > + return of_platform_populate(np, NULL, NULL, &pdev->dev); As np only used here, I'd not bother with the local variable in this function. > +} > + > +static const struct stm32_sys_bus_match_data stm32mp15_sys_bus_data = { Naming a structure after where it comes from is a little unusual and confusion when a given call gets it from somewhere else. I'd expect it to be named after what sort of thing it contains. stm32_sys_bus_info or something like that. > + .max_entries = STM32MP15_ETZPC_ENTRIES, > +}; > + > +static const struct stm32_sys_bus_match_data stm32mp13_sys_bus_data = { > + .max_entries = STM32MP13_ETZPC_ENTRIES, > +}; > + > +static const struct of_device_id stm32_sys_bus_of_match[] = { > + { .compatible = "st,stm32mp15-sys-bus", .data = &stm32mp15_sys_bus_data }, > + { .compatible = "st,stm32mp13-sys-bus", .data = &stm32mp13_sys_bus_data }, Alphabetical order usually preferred when there isn't a strong reason for another choice. > + {} > +}; > +MODULE_DEVICE_TABLE(of, stm32_sys_bus_of_match); > + > +static struct platform_driver stm32_sys_bus_driver = { > + .probe = stm32_sys_bus_probe, > + .driver = { > + .name = "stm32-sys-bus", > + .of_match_table = stm32_sys_bus_of_match, > + }, > +}; > + > +static int __init stm32_sys_bus_init(void) > +{ > + return platform_driver_register(&stm32_sys_bus_driver); > +} > +arch_initcall(stm32_sys_bus_init); > + Unwanted trailing blank line.
On Tue, 7 Feb 2023 15:12:23 +0100 Gatien CHEVALLIER <gatien.chevallier@foss.st.com> wrote: > Hi Jonathan, > > On 1/28/23 17:12, Jonathan Cameron wrote: > > On Fri, 27 Jan 2023 17:40:38 +0100 > > Gatien Chevallier <gatien.chevallier@foss.st.com> wrote: > > > >> This driver is checking the access rights of the different > >> peripherals connected to the system bus. If access is denied, > >> the associated device tree node is skipped so the platform bus > >> does not probe it. > >> > >> Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com> > >> Signed-off-by: Loic PALLARDY <loic.pallardy@st.com> > > > > Hi Gatien, > > > > A few comments inline, > > > > Thanks, > > > > Jonathan > > > >> diff --git a/drivers/bus/stm32_sys_bus.c b/drivers/bus/stm32_sys_bus.c > >> new file mode 100644 > >> index 000000000000..c12926466bae > >> --- /dev/null > >> +++ b/drivers/bus/stm32_sys_bus.c > >> @@ -0,0 +1,168 @@ > >> +// SPDX-License-Identifier: GPL-2.0 > >> +/* > >> + * Copyright (C) 2023, STMicroelectronics - All Rights Reserved > >> + */ > >> + > >> +#include <linux/bitfield.h> > >> +#include <linux/bits.h> > >> +#include <linux/device.h> > >> +#include <linux/err.h> > >> +#include <linux/io.h> > >> +#include <linux/init.h> > >> +#include <linux/kernel.h> > >> +#include <linux/module.h> > >> +#include <linux/of.h> > >> +#include <linux/of_platform.h> > >> +#include <linux/platform_device.h> > >> + > >> +/* ETZPC peripheral as firewall bus */ > >> +/* ETZPC registers */ > >> +#define ETZPC_DECPROT 0x10 > >> + > >> +/* ETZPC miscellaneous */ > >> +#define ETZPC_PROT_MASK GENMASK(1, 0) > >> +#define ETZPC_PROT_A7NS 0x3 > >> +#define ETZPC_DECPROT_SHIFT 1 > > > > This define makes the code harder to read. What we care about is > > the number of bits in the register divided by number of entries. > > (which is 2) hence the shift by 1. See below for more on this. > > > > > >> + > >> +#define IDS_PER_DECPROT_REGS 16 > > > >> +#define STM32MP15_ETZPC_ENTRIES 96 > >> +#define STM32MP13_ETZPC_ENTRIES 64 > > > > These defines just make the code harder to check. > > They aren't magic numbers, but rather just telling us how many > > entries there are, so I would just put them in the structures directly. > > Their use make it clear what they are without needing to give them a name. > > > > Honestly, I'd rather read the hardware configuration registers to get > this information instead of differentiating MP13/15. Would you agree on > that? Sure, if they are discoverable even better.
diff --git a/MAINTAINERS b/MAINTAINERS index 5b74014994f5..aafe32aa1925 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -19782,6 +19782,12 @@ L: linux-spi@vger.kernel.org S: Maintained F: drivers/spi/spi-stm32.c +ST STM32 SYS BUS DRIVER +M: Gatien Chevallier <gatien.chevallier@foss.st.com> +S: Maintained +F: Documentation/devicetree/bindings/bus/st,sys-bus.yaml +F: drivers/bus/stm32_sys_bus.c + ST STPDDC60 DRIVER M: Daniel Nilsson <daniel.nilsson@flex.com> L: linux-hwmon@vger.kernel.org diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig index 7bfe998f3514..3f7bc1f67916 100644 --- a/drivers/bus/Kconfig +++ b/drivers/bus/Kconfig @@ -163,6 +163,15 @@ config QCOM_SSC_BLOCK_BUS i2c/spi/uart controllers, a hexagon core, and a clock controller which provides clocks for the above. +config STM32_SYS_BUS + bool "STM32 System bus controller" + depends on ARCH_STM32 || COMPILE_TEST + default MACH_STM32MP157 || MACH_STM32MP13 + help + Say y to enable device access right verification before device probing. + If access not granted, device won't be probed and an error message will + provide the reason. + config SUN50I_DE2_BUS bool "Allwinner A64 DE2 Bus Driver" default ARM64 diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile index d90eed189a65..b15fdc42d0be 100644 --- a/drivers/bus/Makefile +++ b/drivers/bus/Makefile @@ -26,6 +26,7 @@ obj-$(CONFIG_OMAP_INTERCONNECT) += omap_l3_smx.o omap_l3_noc.o obj-$(CONFIG_OMAP_OCP2SCP) += omap-ocp2scp.o obj-$(CONFIG_QCOM_EBI2) += qcom-ebi2.o obj-$(CONFIG_QCOM_SSC_BLOCK_BUS) += qcom-ssc-block-bus.o +obj-$(CONFIG_STM32_SYS_BUS) += stm32_sys_bus.o obj-$(CONFIG_SUN50I_DE2_BUS) += sun50i-de2.o obj-$(CONFIG_SUNXI_RSB) += sunxi-rsb.o obj-$(CONFIG_OF) += simple-pm-bus.o diff --git a/drivers/bus/stm32_sys_bus.c b/drivers/bus/stm32_sys_bus.c new file mode 100644 index 000000000000..c12926466bae --- /dev/null +++ b/drivers/bus/stm32_sys_bus.c @@ -0,0 +1,168 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2023, STMicroelectronics - All Rights Reserved + */ + +#include <linux/bitfield.h> +#include <linux/bits.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_platform.h> +#include <linux/platform_device.h> + +/* ETZPC peripheral as firewall bus */ +/* ETZPC registers */ +#define ETZPC_DECPROT 0x10 + +/* ETZPC miscellaneous */ +#define ETZPC_PROT_MASK GENMASK(1, 0) +#define ETZPC_PROT_A7NS 0x3 +#define ETZPC_DECPROT_SHIFT 1 + +#define IDS_PER_DECPROT_REGS 16 +#define STM32MP15_ETZPC_ENTRIES 96 +#define STM32MP13_ETZPC_ENTRIES 64 + +struct sys_bus_data; + +struct stm32_sys_bus_match_data { + unsigned int max_entries; +}; + +struct sys_bus_data { + const struct stm32_sys_bus_match_data *pconf; + void __iomem *sys_bus_base; + struct device *dev; +}; + +static int stm32_sys_bus_get_periph_id(struct sys_bus_data *pdata, struct device_node *np, u32 *id) +{ + int err; + u32 feature_domain_cell[2]; + u32 id_bus; + + /* Get reg from device node */ + err = of_property_read_u32_array(np, "feature-domains", feature_domain_cell, 2); + if (err) { + dev_err(pdata->dev, "Unable to find feature-domains property\n"); + return -ENODEV; + } + + id_bus = feature_domain_cell[1]; + + if (id_bus >= pdata->pconf->max_entries) { + dev_err(pdata->dev, "Invalid sys bus ID for %s\n", np->full_name); + return -EINVAL; + } + + *id = id_bus; + + return 0; +} + +static int stm32_etzpc_get_access(struct sys_bus_data *pdata, struct device_node *np) +{ + int err; + u32 offset, reg_offset, sec_val, id; + + err = stm32_sys_bus_get_periph_id(pdata, np, &id); + if (err) + return err; + + /* Check access configuration, 16 peripherals per register */ + reg_offset = ETZPC_DECPROT + 0x4 * (id / IDS_PER_DECPROT_REGS); + offset = (id % IDS_PER_DECPROT_REGS) << ETZPC_DECPROT_SHIFT; + + /* Verify peripheral is non-secure and attributed to cortex A7 */ + sec_val = (readl(pdata->sys_bus_base + reg_offset) >> offset) & ETZPC_PROT_MASK; + if (sec_val != ETZPC_PROT_A7NS) { + dev_dbg(pdata->dev, "Invalid bus configuration: reg_offset %#x, value %d\n", + reg_offset, sec_val); + return -EACCES; + } + + return 0; +} + +static void stm32_sys_bus_populate(struct sys_bus_data *pdata) +{ + struct device *parent; + struct device_node *child; + + parent = pdata->dev; + + dev_dbg(parent, "Populating %s system bus\n", pdata->dev->driver->name); + + for_each_available_child_of_node(dev_of_node(parent), child) { + if (stm32_etzpc_get_access(pdata, child)) { + /* + * Peripheral access not allowed. + * Mark the node as populated so platform bus won't probe it + */ + of_node_set_flag(child, OF_POPULATED); + dev_dbg(parent, "%s: Peripheral will not be probed\n", + child->full_name); + } + } +} + +static int stm32_sys_bus_probe(struct platform_device *pdev) +{ + struct sys_bus_data *pdata; + void __iomem *mmio; + struct device_node *np = pdev->dev.of_node; + + pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); + if (!pdata) + return -ENOMEM; + + mmio = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(mmio)) + return PTR_ERR(mmio); + + pdata->sys_bus_base = mmio; + pdata->pconf = of_device_get_match_data(&pdev->dev); + pdata->dev = &pdev->dev; + + platform_set_drvdata(pdev, pdata); + + stm32_sys_bus_populate(pdata); + + /* Populate all available nodes */ + return of_platform_populate(np, NULL, NULL, &pdev->dev); +} + +static const struct stm32_sys_bus_match_data stm32mp15_sys_bus_data = { + .max_entries = STM32MP15_ETZPC_ENTRIES, +}; + +static const struct stm32_sys_bus_match_data stm32mp13_sys_bus_data = { + .max_entries = STM32MP13_ETZPC_ENTRIES, +}; + +static const struct of_device_id stm32_sys_bus_of_match[] = { + { .compatible = "st,stm32mp15-sys-bus", .data = &stm32mp15_sys_bus_data }, + { .compatible = "st,stm32mp13-sys-bus", .data = &stm32mp13_sys_bus_data }, + {} +}; +MODULE_DEVICE_TABLE(of, stm32_sys_bus_of_match); + +static struct platform_driver stm32_sys_bus_driver = { + .probe = stm32_sys_bus_probe, + .driver = { + .name = "stm32-sys-bus", + .of_match_table = stm32_sys_bus_of_match, + }, +}; + +static int __init stm32_sys_bus_init(void) +{ + return platform_driver_register(&stm32_sys_bus_driver); +} +arch_initcall(stm32_sys_bus_init); +