Messages in this thread | | | Date | Thu, 8 Sep 2022 12:26:37 -0300 | From | Wander Lairson Costa <> | Subject | Re: [PATCH 2/5] drivers/auxdisplay: sensehat: Raspberry Pi Sense HAT display driver |
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On Tue, Aug 23, 2022 at 01:41:55PM -0400, Charles Mirabile wrote: > This patch adds the driver for the 8x8 RGB LED matrix display > on the Sense HAT. It appears as a character device named sense-hat > in /dev/. That special file is 192 bytes large and contains 64 > RGB triplets (3 bytes each) one for each pixel in row major order. > > Co-developed-by: Joel Savitz <jsavitz@redhat.com> > Signed-off-by: Joel Savitz <jsavitz@redhat.com> > Signed-off-by: Charles Mirabile <cmirabil@redhat.com> > --- > drivers/auxdisplay/Kconfig | 8 + > drivers/auxdisplay/Makefile | 1 + > drivers/auxdisplay/sensehat-display.c | 205 ++++++++++++++++++++++++++ > 3 files changed, 214 insertions(+) > create mode 100644 drivers/auxdisplay/sensehat-display.c > > diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig > index 64012cda4d12..9bad1aade7a0 100644 > --- a/drivers/auxdisplay/Kconfig > +++ b/drivers/auxdisplay/Kconfig > @@ -203,6 +203,14 @@ config ARM_CHARLCD > line and the Linux version on the second line, but that's > still useful. > > +config SENSEHAT_DISPLAY > + tristate "Raspberry Pi Sense HAT display driver" > + depends on I2C > + select MFD_SIMPLE_MFD_I2C > + help > + This is a driver for the Raspberry Pi Sensehat 8x8 RBG-LED matrix > + you can access it as a misc device at /dev/sense-hat > + > menuconfig PARPORT_PANEL > tristate "Parallel port LCD/Keypad Panel support" > depends on PARPORT > diff --git a/drivers/auxdisplay/Makefile b/drivers/auxdisplay/Makefile > index 6968ed4d3f0a..30b2b7934046 100644 > --- a/drivers/auxdisplay/Makefile > +++ b/drivers/auxdisplay/Makefile > @@ -14,3 +14,4 @@ obj-$(CONFIG_HT16K33) += ht16k33.o > obj-$(CONFIG_PARPORT_PANEL) += panel.o > obj-$(CONFIG_LCD2S) += lcd2s.o > obj-$(CONFIG_LINEDISP) += line-display.o > +obj-$(CONFIG_SENSEHAT_DISPLAY) += sensehat-display.o > diff --git a/drivers/auxdisplay/sensehat-display.c b/drivers/auxdisplay/sensehat-display.c > new file mode 100644 > index 000000000000..08c0c4338f3e > --- /dev/null > +++ b/drivers/auxdisplay/sensehat-display.c > @@ -0,0 +1,205 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Raspberry Pi Sense HAT 8x8 LED matrix display driver > + * http://raspberrypi.org > + * > + * Copyright (C) 2015 Raspberry Pi > + * Copyright (C) 2021 Charles Mirabile, Joel Savitz > + * > + * Original Author: Serge Schneider > + * Revised for upstream Linux by: Charles Mirabile, Joel Savitz > + */ > + > +#include <linux/module.h> > +#include <linux/kernel.h> > +#include <linux/errno.h> > +#include <linux/string.h> > +#include <linux/mm.h> > +#include <linux/slab.h> > +#include <linux/uaccess.h> > +#include <linux/delay.h> > +#include <linux/init.h> > +#include <linux/platform_device.h> > +#include <linux/mod_devicetable.h> > +#include <linux/miscdevice.h> > +#include <linux/regmap.h> > +#include <linux/property.h> > + > +#define DISPLAY_SMB_REG 0x00 > +#define RGB_555_MASK 0x1f > +#define NUM_LEDS 8 > +#define NUM_CHANNELS 3 > + > +struct sensehat_display { > + struct platform_device *pdev; > + struct miscdevice mdev; > + struct mutex rw_mtx;
Calling this rw_mtx is misleading, since it is not a rw_mutex. We should rename it to mtx.
> + u8 vmem[NUM_LEDS][NUM_LEDS][NUM_CHANNELS]; > + struct regmap *regmap; > +}; > + > +#define VMEM_SIZE sizeof_field(struct sensehat_display, vmem) > + > + > +static int sensehat_update_display(struct sensehat_display *display) > +{ > + int i, j, k, ret; > + u8 buff[NUM_LEDS][NUM_CHANNELS][NUM_LEDS]; > + > + for (i = 0; i < NUM_LEDS; ++i) > + for (j = 0; j < NUM_LEDS; ++j) > + for (k = 0; k < NUM_CHANNELS; ++k) > + buff[i][k][j] = > + display->vmem[i][j][k] & RGB_555_MASK; > + > + ret = regmap_bulk_write(display->regmap, DISPLAY_SMB_REG, buff, > + VMEM_SIZE); > + if (ret < 0) > + dev_err(&display->pdev->dev, > + "Update to 8x8 LED matrix display failed"); > + return ret; > +} > + > +static loff_t sensehat_display_llseek(struct file *filp, loff_t offset, > + int whence) > +{ > + return fixed_size_llseek(filp, offset, whence, VMEM_SIZE); > +} > + > +static ssize_t sensehat_display_read(struct file *filp, char __user *buf, > + size_t count, loff_t *f_pos) > +{ > + struct sensehat_display *sensehat_display = > + container_of(filp->private_data, struct sensehat_display, mdev); > + ssize_t ret = -EFAULT; > + > + if (*f_pos < 0 || *f_pos >= VMEM_SIZE) > + return 0;
Maybe it should return -EINVAL?
> + count = min_t(size_t, count, VMEM_SIZE - *f_pos); > + > + if (mutex_lock_interruptible(&sensehat_display->rw_mtx)) > + return -ERESTARTSYS; > + if (copy_to_user(buf, *f_pos + (u8 *)sensehat_display->vmem, count)) > + goto out; > + *f_pos += count; > + ret = count; > +out: > + mutex_unlock(&sensehat_display->rw_mtx); > + return ret; > +} > + > +static ssize_t sensehat_display_write(struct file *filp, const char __user *buf, > + size_t count, loff_t *f_pos) > +{ > + struct sensehat_display *sensehat_display = > + container_of(filp->private_data, struct sensehat_display, mdev); > + int ret = -EFAULT; > + > + if (*f_pos < 0 || *f_pos >= VMEM_SIZE) > + return -EFBIG; > + count = min_t(size_t, count, VMEM_SIZE - *f_pos); > + > + if (mutex_lock_interruptible(&sensehat_display->rw_mtx)) > + return -ERESTARTSYS; > + if (copy_from_user(*f_pos + (u8 *)sensehat_display->vmem, buf, count)) > + goto out; > + ret = sensehat_update_display(sensehat_display); > + if (ret < 0) { > + ret = -EIO; > + goto out; > + } > + *f_pos += count; > + ret = count; > +out: > + mutex_unlock(&sensehat_display->rw_mtx); > + return ret; > +} > + > +static const struct file_operations sensehat_display_fops = { > + .owner = THIS_MODULE, > + .llseek = sensehat_display_llseek, > + .read = sensehat_display_read, > + .write = sensehat_display_write, > +}; > + > +static int sensehat_display_probe(struct platform_device *pdev) > +{ > + int ret; > + > + struct sensehat_display *sensehat_display = > + devm_kmalloc(&pdev->dev, sizeof(*sensehat_display), GFP_KERNEL); > + if (!sensehat_display) > + return -ENOMEM; > + > + sensehat_display->pdev = pdev; > + > + dev_set_drvdata(&pdev->dev, sensehat_display); > + > + sensehat_display->regmap = dev_get_regmap(pdev->dev.parent, NULL); > + if (!sensehat_display->regmap) { > + dev_err(&pdev->dev, > + "unable to get sensehat regmap"); > + return -ENODEV; > + } > + > + memset(sensehat_display->vmem, 0, VMEM_SIZE); > + > + mutex_init(&sensehat_display->rw_mtx); > + > + ret = sensehat_update_display(sensehat_display); > + if (ret < 0) { > + dev_err(&pdev->dev, > + "Could not communicate with sensehat"); > + return ret; > + } > + > + sensehat_display->mdev = (struct miscdevice){ > + .minor = MISC_DYNAMIC_MINOR, > + .name = "sense-hat", > + .mode = 0666, > + .fops = &sensehat_display_fops, > + }; > + > + ret = misc_register(&sensehat_display->mdev); > + if (ret < 0) { > + dev_err(&pdev->dev, > + "Could not register 8x8 LED matrix display."); > + return ret; > + } > + > + dev_info(&pdev->dev, > + "8x8 LED matrix display registered with minor number %i", > + sensehat_display->mdev.minor); > + > + return 0; > +} > + > +static int sensehat_display_remove(struct platform_device *pdev) > +{ > + struct sensehat_display *sensehat_display = dev_get_drvdata(&pdev->dev); > + > + misc_deregister(&sensehat_display->mdev); > + return 0; > +} > + > +static const struct of_device_id sensehat_display_device_id[] = { > + { .compatible = "raspberrypi,sensehat-display" }, > + {}, > +}; > +MODULE_DEVICE_TABLE(of, sensehat_display_device_id); > + > +static struct platform_driver sensehat_display_driver = { > + .probe = sensehat_display_probe, > + .remove = sensehat_display_remove, > + .driver = { > + .name = "sensehat-display", > + .of_match_table = sensehat_display_device_id, > + }, > +}; > + > +module_platform_driver(sensehat_display_driver); > + > +MODULE_DESCRIPTION("Raspberry Pi Sense HAT 8x8 LED matrix display driver"); > +MODULE_AUTHOR("Charles Mirabile <cmirabil@redhat.com>"); > +MODULE_AUTHOR("Serge Schneider <serge@raspberrypi.org>"); > +MODULE_LICENSE("GPL"); > -- > 2.31.1 > >
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