Re: [PATCH 3/7] stm32mp1: rng: Add a driver for random number generator(rng) device

Hi Sughosh

On 12/4/19 12:53 PM, Sughosh Ganu wrote:

Add a driver for the rng device found on stm32mp1 platforms. The driver provides a routine for reading the random number seed from the hardware device.

Signed-off-by: Sughosh Ganu sughosh.ganu@linaro.org

drivers/rng/Kconfig | 7 ++ drivers/rng/Makefile | 1 + drivers/rng/stm32mp1_rng.c | 164 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 172 insertions(+) create mode 100644 drivers/rng/stm32mp1_rng.c

diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig index dd44cc0..5fc11db 100644 --- a/drivers/rng/Kconfig +++ b/drivers/rng/Kconfig @@ -5,3 +5,10 @@ config DM_RNG Enable driver model for random number generator(rng) devices. This interface is used to initialise the rng device and to read the random seed from the device.

+config RNG_STM32MP1

•   bool "Enable random number generator for STM32MP1"
  

•   depends on ARCH_STM32MP && DM_RNG
  

•   default n
  

•   help
  

•     Enable STM32MP1 rng driver.
  

diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile index 311705b..699beb3 100644 --- a/drivers/rng/Makefile +++ b/drivers/rng/Makefile @@ -4,3 +4,4 @@ #

obj-$(CONFIG_DM_RNG) += rng-uclass.o +obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o diff --git a/drivers/rng/stm32mp1_rng.c b/drivers/rng/stm32mp1_rng.c new file mode 100644 index 0000000..f5ee084 --- /dev/null +++ b/drivers/rng/stm32mp1_rng.c @@ -0,0 +1,164 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/*

• • Copyright (c) 2019, Linaro Limited
• */

+#include <common.h> +#include <clk.h> +#include <dm.h> +#include <reset.h> +#include <rng.h>

+#include <asm/io.h> +#include <linux/iopoll.h> +#include <linux/kernel.h>

+#define RNG_CR 0x00 +#define RNG_CR_RNGEN BIT(2) +#define RNG_CR_CED BIT(5)

+#define RNG_SR 0x04 +#define RNG_SR_SEIS BIT(6) +#define RNG_SR_CEIS BIT(5) +#define RNG_SR_SECS BIT(2) +#define RNG_SR_DRDY BIT(0)

+#define RNG_DR 0x08

+struct stm32_rng_platdata {

• fdt_addr_t base;
• struct clk clk;
• struct reset_ctl rst;
• bool inited;

+};

+static int stm32_rng_read(struct udevice *dev, void *data, size_t len) +{

• int retval = 0, i;
• u32 sr, count, reg;
• size_t increment;
• struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
• while (len > 0) {

• retval = readl_poll_timeout(pdata->base + RNG_SR, sr,
  

• 			    sr & RNG_SR_DRDY, 10000);
  

• if (retval)
  

• 	return retval;
  

• if (sr & (RNG_SR_SEIS | RNG_SR_SECS)) {
  

• 	/* As per SoC TRM */
  

• 	clrbits_le32(pdata->base + RNG_SR, RNG_SR_SEIS);
  

• 	for (i = 0; i < 12; i++)
  

• 		readl(pdata->base + RNG_DR);
  

• 	if (readl(pdata->base + RNG_SR) & RNG_SR_SEIS) {
  

• 		printf("RNG Noise");
  

• 		return -EIO;
  

• 	}
  

• 	/* start again */
  

• 	continue;
  

• }
  

• count = 4;
  

• while (len && count) {
  

• 	reg = readl(pdata->base + RNG_DR);
  

• 	memcpy(data, &reg, min(len, sizeof(u32)));
  

• 	increment = min(len, sizeof(u32));
  

• 	data += increment;
  

• 	retval += increment;
  

• 	len -= increment;
  

• 	count--;
  

• }
  

• }
• return retval;

+}

+static int stm32_rng_init(struct stm32_rng_platdata *pdata) +{

• int err;
• err = clk_enable(&pdata->clk);
• if (err)

• return err;
  

• /* Disable CED */
• writel(RNG_CR_RNGEN | RNG_CR_CED, pdata->base + RNG_CR);
• /* clear error indicators */
• writel(0, pdata->base + RNG_SR);
• pdata->inited = 1;
• return 0;

+}

+static int stm32_rng_cleanup(struct stm32_rng_platdata *pdata) +{

• writel(0, pdata->base + RNG_CR);
• return clk_disable(&pdata->clk);

+}

+static int stm32_rng_probe(struct udevice *dev) +{

• struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
• if (pdata->inited)

• return 0;
  

No need to protect stm32_rng_probe() for re-entrance, DM is taking care of that, so pdata->inited field can be removed.

Thanks

• reset_assert(&pdata->rst);
• udelay(20);
• reset_deassert(&pdata->rst);
• return stm32_rng_init(pdata);

+}

+static int stm32_rng_remove(struct udevice *dev) +{

• struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
• return stm32_rng_cleanup(pdata);

+}

+static int stm32_rng_ofdata_to_platdata(struct udevice *dev) +{

• struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
• int err;
• pdata->base = dev_read_addr(dev);
• if (!pdata->base)

• return -ENOMEM;
  

• err = clk_get_by_index(dev, 0, &pdata->clk);
• if (err)

• return err;
  

• err = reset_get_by_index(dev, 0, &pdata->rst);
• if (err)

• return err;
  

• return 0;

+}

+static const struct dm_rng_ops stm32_rng_ops = {

• .read = stm32_rng_read,

+};

+static const struct udevice_id stm32_rng_match[] = {

• {

• .compatible = "st,stm32-rng",
  

• },
• {},

+};

+U_BOOT_DRIVER(stm32_rng) = {

• .name = "stm32-rng",
• .id = UCLASS_RNG,
• .of_match = stm32_rng_match,
• .ops = &stm32_rng_ops,
• .probe = stm32_rng_probe,
• .remove = stm32_rng_remove,
• .platdata_auto_alloc_size = sizeof(struct stm32_rng_platdata),
• .ofdata_to_platdata = stm32_rng_ofdata_to_platdata,

+};